Combat Soldiers, Particularly in Iraq and Afghanistan, Have Been Found

Combat soldiers, particularly in Iraq and Afghanistan, have been found to have high rates of PTSD. This is because

A) soldiers have higher rates of preexisting mental conditions than the general population.
B) soldiers have personality traits that make them more at risk.
C) combat situations involve many factors that create intense stress, including fear, loss of security and lack of sleep.
D) combat situations expose soldiers to many physical substances linked to PTSD.