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
[{'content': 'Strengthening muscle exercise \nSelect and explain. \nA. Isotonic, B. Isometric, C. Aerobic, D. None', 'role': 'user'}, {'content': "Answer: A \nExplanation: Contraction against a constant load with change in muscle length is isotonic. Since work done is product of force times distance, isotonic contraction do work. (REF: GANONG'S REVIEW OF MEDICAL PHYSIOLOGY 24 EDITION, PAGE NO - 104)", 'role': 'assistant'}]