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
Golgi tendon apparatus conveys message to CNS, depends upon: 
Select and explain. 
A. Tension in muscle, B. Length of muscle, C. Rapidity of contraction, D. Blood supply
A: Tension in muscle
Answer: A: Tension in muscle 
Explanation: Golgi tendon organs are in series with the muscle fibers, they are stimulated by both passive stretch and active contraction of the muscle, when  tension increases inside muscle.