Which Statement Differentiates Combat-Related Trauma from Non-Combat-Related Trauma

Which statement differentiates combat-related trauma from non-combat-related trauma?

A) One may have been deployed to a war zone or combat area.
B) One must have had one's life at risk to protect combat peers.
C) One may have been directly involved in a combat scenario.
D) One perceives that one is guilty or responsible for the event.