What is not a function of the F-bit on DS1 using Extended Super Frame (ESF)?

A.
It is used for signaling on-hook and off-hook status

B.
It is used for a frame’s synchronization and alignment

C.
It is used for control and performance information

D.
It carries CRC information for error detection

Explanation:
ESF extends the DS1 framing from 12 to 24 frames so that an 8-kbps F-Bit pattern can be used for three separate functions: Framing, CRC and data link.