Does Amazon DynamoDB support both increment and decrement atomic operations?

A.
No, neither increment nor decrement operations.

B.
Only increment, since decrement are inherently impossible with DynamoDB’s data model.

C.
Only decrement, since increment are inherently impossible with DynamoDB’s data model.

D.
Yes, both increment and decrement operations.

Explanation:
Amazon DynamoDB supports increment and decrement atomic operations.
http://docs.aws.amazon.com/amazondynamodb/latest/developerguide/APISummary.html