In a 63-Year-Old Man, a Magnetic Resonance Imaging Scan of the Lower

In a 63-year-old man, a magnetic resonance imaging scan of the lower thoracic region of the vertebral column reveals the presence of a tumor pressing on the lumbar segments of the spinal cord. He has a loss of sensation in the skin over the anterior surface of the left thigh and is unable to extend his left knee joint. Examination reveals that the muscles of the front of the left thigh have atrophied and have no tone and that the left knee jerk is absent.
-The following statements concerning this patient are correct except which?

A) The tumor is interrupting the normal function of the efferent motor fibers of the spinal cord on the left side.
B) The quadriceps femoris muscles on the front of the left thigh are atrophied.
C) The loss of skin sensation is confined to the dermatomes L1, 2, 3, and 4.
D) The absence of the left knee jerk is because of involvement of the first lumbar spinal segment.