Jake, a veteran of the Iraq war, witnessed his friends being severely injured or killed on two tours ...

Jake, a veteran of the Iraq war, witnessed his friends being severely injured or killed on two tours of duty. He came home physically healthy but suffering from PTSD. Jake was not much of a drinker before he went to Iraq, but now, he frequently drinks alone at night. To what might this be related?
 
  a. excessive levels of naturally occurring benzodiazepine activity in the frontal cortex
  b. lower levels of naturally occurring benzodiazepine activity in the frontal cortex
  c. excessive levels of naturally occurring benzodiazepine activity in the hippocampus
  d. lower levels of naturally occurring benzodiazepine activity in the hippocampus