Answer: C. Flexibility
Explanation:
The sit and reach test is a common measure of flexibility, and specifically measures the flexibility of the lower back and hamstring muscles. This test is important as because tightness in this area is implicated in lumbar lordosis, forward pelvic tilt and lower back pain.
The corticospinal tract carries motor signals from the primary motor cortex in the brain, down the spinal cord, to the muscles of the trunk and limbs. And The corticobulbar tract carries efferent, motor, information from the primary motor cortex to the muscles of the face, head and neck.
I believe its low zinc levels