Which diagnosis includes a breakdown in sense of self, a significant alteration in memory or identity, and even a separation of one part of the identity from another part?

A) Mood disorder
B) Personality disorder
C) Dissociative disorder
D) Histrionic personality disorder

Dissociative disorders are characterized by a disruption of and/or discontinuity in the normal integration of consciousness, memory, identity, emotion, perception, body representation, motor control, and behavior. This includes a breakdown in the sense of self, significant alterations in memory or identity, and potentially a separation of one part of the identity from another part, fitting the description given.