This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
muscle spindle is 
Select and explain. 
A. Receptor for a variety of multisynaptic reflexes, B. Receptor for stretch receptor reflex, C. Occurs only in antigravity extensor muscles, D. Excited by both stretch and contraction of the muscles in which it is located
B: Receptor for stretch receptor reflex
Answer: B: Receptor for stretch receptor reflex 
Explanation: None