If an operating room nurse is to assist a patient to the Trendelenburg position, he or she would place him:

A、flat on his back with his arms next to his sides;

B、on his back with his head lowered so that the plane of his body meets the horizontal on an angle;

C、on his back with his legs and thighs flexed at right angles;

D、on his side with his uppermost leg adducted and flexed at the knee.