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 RevokeSecurityGroup Ingress
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.

Answer: C