This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
Active tension in a muscle depends upon which of the following 
Select and explain. 
A. Number of muscle fibres, B. Number of motor units recruited, C. Aerobic capacity of muscle, D. Action potential amplitude
B: Number of motor units recruited
Answer: B: Number of motor units recruited 
Explanation: Active Tension in a muscle depends upon the number of motor units recruited. The greater the number of motor units recruited, the greater will be the active tension. Factors Determining Muscle Tension (Active Tension) Tension developed by each fiber Action potential frequency Fibre length (Length-tension relationship) Fibre length Fatigue Number of active fibers Number of fibers per motor unit Number of active motor units (recruitment) Ref: Vander's Human physiology: The Mechanisms of Body function 11th edition Pgno: 276