11. During the knee-jerk reflex in a seated individual, as the lower leg moves from a vertical to a horizontal position, what happens to the muscles of the quadriceps (located on the front of the thigh) and the hamstring muscles (located on the back of the thigh)? (A) Both the quadriceps and hamstrings are excited and contracting. (B) Both the quadriceps and hamstrings are inhibited and relaxed. (C) The quadriceps are excited, while the hamstrings are inhibited. (D) The quadriceps are inhibited, while the hamstrings are excited. (E) The quadriceps and hamstrings alternate between excitation and inhibition in a rhythmic cycle.