Which command will display the CHAP authentication process as it occur between two routers in the network?

All WAN links inside the ABC University network use PPP with CHAP for authentication security. Which command will display the CHAP authentication process as it occur between two routers in the network?

A.
show chap authentication

B.
show interface serial0

C.
debug ppp authentication

D.
debug chap authentication

E.
show ppp authentication chap