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': 'Twitch of a single motor unit is called: \nSelect and explain. \nA. Myoclonic jerk, B. Fasciculation, C. Tremor, D. Chorea', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Fasciculations are jerky, visible contractions of groups of muscle fibers that occur as a result of pathologic discharge of spinal motor neurons. Fibrillations are fine, irregular contractions of individual muscle fibers. They may occur due to denervation hypersensitivity resulting from LMN lesion. Usually, the contractions are not visible grossly. Myoclonic jerk or clonus: Regular, rhythmic contractions of a muscle (entire muscle) subjected to sudden, maintained stretch. It is due to increased g-efferent discharge.', 'role': 'assistant'}]