Which EBS volume type is best for high performance NoSQL cluster deployments?

io1 volumes, or Provisioned IOPS (PIOPS) SSDs, are best for: Critical business applications that require sustained IOPS performance, or more than 10,000 IOPS or 160 MiB/s of throughput per volume, like large database workloads, such as http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/EBSVolumeTypes.html

A.
io1

B.
gp1

C.
standard

D.
gp2

Explanation:
Explanation/Reference:
MongoDB.