What is the proper format of a custom auto-attendant prompt?

A.	G.711 u-law,8 kHZ, 8-bit, mono
B.	G.711 a-law,8 kHz, 16-bit, mono
C.	G.711 a-law,16 kHZ, 8-bit, stereo
D.	G.729 ,8 kHZ, 8-bit, mono