Which of the following events in a stretch reflex occurs last?

A) Alpha motor neurons transmit action potentials to muscle causing contraction.
B) Muscle spindle detects stretch of muscle.
C) Afferent neurons conduct action potentials to the spinal cord.
D) Afferent neurons synapse with alpha motor neurons.
E) Muscle is stretched.

The sequence of events in a stretch reflex starts with the muscle being stretched (E), which is then detected by the muscle spindle (B). This detection leads to afferent neurons conducting action potentials to the spinal cord (C), where they synapse with alpha motor neurons (D). Finally, alpha motor neurons transmit action potentials to the muscle, causing it to contract (A). Therefore, the contraction of the muscle as a result of action potentials transmitted by alpha motor neurons occurs last.