In order to optimize performance for a compute cluster that requires low inter-node latency, which of the following feature should you use?

In order to optimize performance for a compute cluster that requires low inter-node latency, which of the following feature should you use?
A . Multiple Availability Zones
B . AWS Direct Connect
C . EC2 Dedicated Instances
D . Placement Groups
E . VPC private subnets

Answer: D

Explanation:

Reference: http://aws.amazon.com/ec2/faqs/ (enhanced networking)