A conscious victim who has suffered a blow to the head has symptoms that indicate the possibility of concussion. If the patient feels no indication of neck or spine injury，recommended treatment would include（）.

A.turning the victim's head to the side to keep his airway open
B.positioning the victim so the head is lower than the body
C.giving the victim water if he is thirsty，but no food
D.elevating the head and shoulders slightly with a pillow