Which of the following statements best characterizes what we know about the origins and development of posttraumatic stress disorder?
1) Cases of PTSD seem to be the result of impaired cognitive functioning or neurological functioning that was present prior to the trauma, and were triggered by the traumatic event.
2) The majority of combat veterans who experienced the horrors of war develop PTSD.
3) Childhood trauma accounts for the majority of cases (about 60 percent) of PTSD.
4) PTSD is caused by a single genetic variant that makes the peripheral nervous system hyperactive.
