Ethernet uses Carrier Sense Multiple Access with Collision Detection (CSMA/CD) to minimize the effect of broadcast collisions.
The following answers are incorrect:
CSU/DSU Is incorrect because Channel Service Unit/Digital Service Unit(CSU/DSU) is a digital interface normally used to connect a router to a digital circuit.
TCP/IP Is incorrect because Transmission Control Protocol/Internet Protocol(TCP/IP) is a network protocol not an access method.
FIFO Is incorrect as it is a distractor. First In, First Out (FIFO) is typically a processing methodology in which first come, first served.
Ethernet is a frame based network technology.
References: OIG CBK Telecommunications and Network Security (pages 437 -438) Wikipedia http://en.wikipedia.org/wiki/FIFO