Immediately after being struck by a motor vehicle, a patient is unconscious, but the patient regains consciousness before arriving at the hospital and appears alert and oriented. The next morning, the patient is confused and demonstrates impaired responsiveness. The patient's history and symptoms support which medical diagnosis?
A. Mild concussion.
B. Subdural hematoma.
C. Extradural (epidural) hematoma.
D. Mild diffuse axonal injury.