Which disorder is a psychological response to a trauma such as a life-threatening accident, a natural disaster, sexual assault, or gun violence that leads to repeated reliving of the incident and persistent psychological symptoms that interfere with normal functioning?

Post-traumatic stress disorder

Explanation:

Post-traumatic stress disorder (PTSD) is a mental condition developed after a person witnesses or experiences a traumatizing event. Symptoms usually appear months after the event took place, sometimes even years afterwards. Those symptoms include: physical reactions and emotional distress, flashbacks and nightmares about the event, hopelessness about the future, etc.