Answer:
Motor neuron.
Explanation:
Motor neuron is a nerve impulse that transfer the messages from the central nervous system to the effector organ. The effector organ can be any muscles, gland or tissue.
The ventral root of reflex arc that controls the leg movement is severed, motor neuron pathway blocks the nerve impulse because the information cannot be transferred from the CNS to the leg.
Thus, the correct answer is option (1).
