When Electrical Maintenance Is Performed, Lockout/tagout Procedures

When electrical maintenance is performed, lockout/tagout procedures:

A) lock out of service those circuits to be worked on so that no one can accidentally energize the circuits.
B) need not be followed in the United States.
C) ensure that no unauthorized persons enter the room where the maintenance work is being done.
D) are used to block access to electrical panels in transformer rooms.