It Is Believed That the Incidence of Combat Exhaustion During

It is believed that the incidence of combat exhaustion during WWII has been underestimated because

A) there was a debate as to how to differentiate between combat exhaustion and PTSD.
B) many men were treated in the field and never formally diagnosed.
C) those who were discharged for medical reasons were not counted when estimates were made.
D) many men who were diagnosed with the brain disorder "shell shock" were probably suffering from combat exhaustion.