The two operations that can be performed on a semaphore variable are select and increment (P and V).

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.

Up to this point, the _______________ collision avoidance method is implemented in Wi-Fi devices.

Fill in the blank(s) with the appropriate word(s).