This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Muscle, Subject name: Physiology
[{'content': 'Resting muscle length means? \nSelect and explain. \nA. Length of actin and myosin before contraction, B. The length of the muscle fiber at the onset of contraction which is required to attain maximum active tension, C. It is about 4 micrometers, D. Length at which muscle has minimal tension', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Resting length: The length of the muscle fiber at the onset of contraction which is required to attain maximum active tension It is about 2 micrometers. Also known as optimum length. At this state, the ends of actin filaments extending from 2 successive Z disks barely overlap one another.', 'role': 'assistant'}]