What statement concerning voice connections is true?

What statement concerning voice connections is true?

A.
Inband dialing format generally requires a greater number of signaling transitions than pulse dialing

B.
Circuit lines utilizing common channel signaling (CCS) use on-hook/off-hook bit mechanisms to notify PBX of connection failures

C.
Single bit errors in PCM samples result in significantly distorted connections

D.
T1 circuits using extended superframe (ESF) can use ABAB signaling or ABCD signaling