A wife of a returning combat veteran called EMS because her husband is complaining of constant headaches. When you ask about post-traumatic stress disorder (PTSD) or traumatic brain injury (TBI), she states that the patient was injured by an improvised explosive device in Iraq, but cannot remember the event. She explains that the patient has undergone numerous CTs and MRIs of head and has been told by his family doctor that there is no sign of injury. Regarding these medical conditions, you realize that:

A) TBI may exist despite the negative findings of the CT and MRI tests
B) PTSD is likely and requires immediate identification and treatment for recovery
C) TBI and PTSD most likely do not exist since the patient does not have any memory of the event
D) TBI and PTSD are not likely since the patient does not have associated symptoms such as dizziness or nausea

A) TBI may exist despite the negative findings of the CT and MRI tests