This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous system, Subject name: Physiology
In stretch reflex, the stimulus is 
Select and explain. 
A. Change in muscle length, B. Change in muscle tension, C. Pain in muscle, D. Cessation of blood supply
A: Change in muscle length
Answer: A: Change in muscle length 
Explanation: The stretch reflex (myotatic reflex) is a muscle contraction in response to stretching within the muscle. It is a monosynaptic reflex which provides automatic regulation of skeletal muscle length.Ref: Ganong&;s review of medical physiology 23rd edition Page no: 158