The different identities or personalities within a person are called d) Alters. This term is usually used in the psychological and medical context of Dissociative Identity Disorder (DID), previously known as multiple personality disorder. But also, in more colloquial terms, one might refer to various addresses used online or social sounds someone can adopt as "masks." So, the correct answer is "Alters" for the psychological context, while in a different context, one might consider "Masks" as an appropriate term.