Alpha and Beta are having a conversation in English. Gamma, who is a gifted conversationalist and tends to monopolize conversations, approaches Alpha and Beta. As soon as Alpha and Beta see Gamma, they start speaking in Spanish, but Gamma does not understand. What did Alpha and Beta just do$?$

A$.$They employed a form of tokenization.

b$.$ They employed a form of encryption.

c$.$ They employed a form of substitution.

d$.$ They employed a form of steganography.