Which failure code is sent in the authentication reject message when a UE with USIM fails to receive the AUTN as part of the authentication and ciphering request from the SGSN?

Which failure code is sent in the authentication reject message when a UE with USIM fails to
receive the AUTN as part of the authentication and ciphering request from the SGSN?

A.
GSM authentication unacceptable

B.
MAC failure

C.
SYNC failure

D.
RAND failure

E.
UMTS authentication unacceptable

Explanation: