Adam works as a Network Administrator. He discovers that the wireless AP transmits 128 bytes of plaintext, and the station responds by encrypting the plaintext. It then transmits the resulting ciphertext using the same key and cipher that are used by WEP to encrypt subsequent network traffic. Which of the following types of authentication mechanism is used here? 

Answer options:

A. Pre-shared key authentication
B. Open system authentication
C. Shared key authentication
D. Single key authentication

C