A gaming application is deployed on four Amazon EC2 instances in a default VPC. The SysOps administrator has noticed consistently high latency in responses as data is transferred among the four instances. There is no way for the administrator to alter the application code.
The MOST effective way to reduce latency is to relaunch the EC2 instances in:

A. a dedicated VPC.
B. a single subnet inside the VPC.
C. a placement group.
D. a single Availability Zone.