Briefing Amazon Knowledge

What does the following command do with respect to the Amazon EC2 security groups?

What does the following command do with respect to the Amazon EC2 security groups?
ec2-revoke RevokeSecurityGroupIngress

A.
Removes one or more security groups from a rule.

B.
Removes one or more security groups from an Amazon EC2 instance.

C.
Removes one or more rules from a security group.

D.
Removes a security group from our account.