Cordelia, an active duty marine, served in Afghanistan. While she was on patrol with her friend, an IED went off, killing her friend and injuring her. In the two months since her friend died, Cordelia has been jumpy, irritable, avoids talking about her friend, and once every few days experiences a flashback to the explosion. Cordelia is experiencing a ________ disorder.

a.antisocial
b.personality mood
c.posttraumatic stress
d.schizotypal personality