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

Explanation:
A placement group is a logical grouping of instances within a single Availability Zone. Using
placement groups enables applications to participate in a low-latency, 10 Gigabits per second
(Gbps) network.
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/placement-groups.html