During voluntary movements, Golgi tendon organ has an impoant role to play because it continuously relays to the efferent neurons:

Explanation

Ans: D. Tension in the muscle(Ref.: Ganong 25/e p232; Guyton 13/e p697, 701).Golgi tendon organ senses muscle tension."The Golgi organ (also called Golgi tendon organ, GTO, tendon organ, neurotendinous organ or neurotendinous spindle) senses changes in muscle tension.It is a proprioceptive sensory receptor organ that is at the origins and inseion of skeletal muscle fibers into the tendons of skeletal muscle. It provides the sensory component of the Golgi tendon reflex.