What is a placement group?

A.
A collection of Auto Scaling groups in the same region

B.
A feature that enables EC2 instances to interact with each other via high bandwidth, low latency
connections

C.
A collection of authorized CloudFront edge locations for a distribution

D.
A collection of Elastic Load Balancers in the same Region or Availability Zone

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. Placement groups are recommended for applications that benefit from low
network latency, high network throughput, or both.
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/placement-groups.html