The correct answer is:

(D) All the above

For repeaters, all of the following statements are true:

• (A) Layer one devices: Repeaters operate at the physical layer (Layer 1) of the OSI model.
• (B) Connect two maximum length segments: Repeaters can connect two segments of a network, each at its maximum length, by amplifying or retransmitting the signal.
• (C) Active powered device: Repeaters require power to operate, as they amplify or regenerate signals to extend the range of a network.