What happens if your application performs more reads or writes than your provisioned capacity?

A.
Nothing.

B.
requests above your provisioned capacity will be performed but you will receive 400 error codes.

C.
requests above your provisioned capacity will be performed but you will receive 200 error codes.

D.
requests above your provisioned capacity will be throttled and you will receive 400 error codes.

Explanation:
Speaking about DynamoDB, if your application performs more reads/second or writes/second than your table’s
provisioned throughput capacity allows, requests above your provisioned capacity will be throttled and you will receive
400 error codes.
http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/ProvisionedThroughputIntro.html