Ethernet is frame based network technology. See below a few definitions from RFC 1122:
SEGMENT A segment is the unit of end-to-end transmission in the TCP protocol. A segment consists of a TCP header followed by application data. A segment is transmitted by encapsulation inside an IP datagram.
PACKET A packet is the unit of data passed across the interface between the internet layer and the link layer. It includes an IP header and data. A packet may be a complete IP datagram or a fragment of an IP datagram.
FRAME A frame is the unit of transmission in a link layer protocol, and consists of a link-layer header followed by a packet.
The following answers are incorrect:
Ethernet segment. Is incorrect because Ethernet segment is a distractor, TCP segment would be the correct terminology. Ethernet is a frame based network technology,
Ethernet datagram. Is incorrect because Ethernet datagram is a distractor, IP datagram would be the correct terminology. Ethernet is a frame based network technology
Ethernet packet. Is incorrect because Ethernet packet is a distractor, a Packet is a group of information so would not be a “single unit”. Ethernet is a frame based network technology.
Look at the diagrams below that were extracted from my Security+ Computer Based Tutorial.
TCP/IP Data Structures

IMPORTANT NOTE: The names used on the diagram above are from RFC 1122 which describe the DOD Model. Vendors and Books may use slightly different names or even number of layers.

TCP/IP Data Structure
The following Reference(s) were used for this question: Wikipedia http://en.wikipedia.org/wiki/Ethernet

If the protocol field has a value of 2 then it would indicate it was IGMP.
The following answers are incorrect:
TCP. Is incorrect because the value for a TCP protocol would be 6. UDP. Is incorrect because the value for an UDP protocol would be 17. ICMP. Is incorrect because the value for an ICMP protocol would be 1.

If the protocol field has a value of 1 then it would indicate it was ICMP.
The following answers are incorrect:
TCP. Is incorrect because the value for a TCP protocol would be 6. UDP. Is incorrect because the value for an UDP protocol would be 17. IGMP. Is incorrect because the value for an IGMP protocol would be 2.

If the protocol field has a value of 6 then it would indicate it was TCP. The protocol field of the IP packet dictates what protocol the IP packet is using.
TCP=6, ICMP=1, UDP=17, IGMP=2
The following answers are incorrect:
ICMP. Is incorrect because the value for an ICMP protocol would be 1. UDP. Is incorrect because the value for an UDP protocol would be 17. IGMP. Is incorrect because the value for an IGMP protocol would be 2.
References: SANS http://www.sans.org/resources/tcpip.pdf?ref=3871

TCP Wrappers can control when a UDP server starts but has little control afterwards because UDP packets can be sent randomly.
The following answers are incorrect:
It stops packets before they reach the application layer, thus confusing some proxy servers. Is incorrect because the TCP Wrapper acts as an ACL restricting packets so would not confuse a proxy server because the packets would not arrive and would not be a limitation.
The hosts. access control system requires a complicated directory tree. Is incorrect because a simple directory tree is involved.
They are too expensive. Is incorrect because TCP Wrapper is considered open source with a BSD licensing scheme.

TCP allows for reliabilty in connections which would be required for terminal emulation. The following answers are incorrect: UDP. Is incorrect because with User Datagram Protocol (UDP) you don’t have a reliable transmission, datagrams could arrive out of sequence. SNMP. Is incorrect because it is a network management protocol, Simple Network Management Protocol (SNMP).
IGP. Is incorrect because Interior Gateway Protocol (IGP) is used interally on a network.

The network layer contains the Internet Protocol (IP), the Internet Control Message Protocol (ICMP), and the Internet Group Management Protocol (IGMP) The following answers are incorrect:
Datagram Layer. Is incorrect as a distractor as there is no Datagram Layer. Transport Layer. Is incorrect because it is used to data between applications and uses the TCP and UDP protocols. Data Link Layer. Is incorrect because this layer deals with addressing hardware.

A bridge operates at the Data Link Layer and a router operates at the Network Layer. The following answers are incorrect: A bridge simply connects multiple networks, a router examines each packet to determine which network to forward it to. Is incorrect because both forward packets this is not distinctive enough.
“Bridge” and “router” are synonyms for equipment used to join two networks. Is incorrect because the two are unique and operate at different layers of the OSI model. The bridge is a specific type of router used to connect a LAN to the global Internet. Is incorrect because a bridge does not connect a LAN to the global internet, but connects networks together creating a LAN.

If the protocol field has a value of 17 then it would indicate it was UDP.
The following answers are incorrect answers:
TCP. Is incorrect because the value for a TCP protocol would be 6. ICMP. Is incorrect because the value for an ICMP protocol would be 1. IGMP. Is incorrect because the value for an IGMP protocol would be 2.
The protocol field of the IP packet dictates what protocol the IP packet is using. TCP=6, ICMP=1, UDP=17, IGMP=2
Reference(s) used for this question: SANS http://www.sans.org/resources/tcpip.pdf?ref=3871

It is the Transport Layer that is responsible for reliable end-to-end data transfer between end systems.
The following answers are incorrect:
Network Layer. Is incorrect because the Network Layer is the OSI layer that is responsible for routing, switching, and subnetwork access across the entire OSI environment.
Data Link Layer. Is incorrect because the Data Link Layer is the serial communications path between nodes or devices without any intermediate switching nodes.
Presentation Layer. Is incorrect because the Presentation Layer is the OSI layer that determines how application information is represented (i.e., encoded) while in transit between two end systems.