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': 'Tetanizing stimulation of the muscle causes a sustained forceful contraction due to: \nSelect and explain. \nA. Recruitment phenomenon, B. Failure of Ca++ removal from the sarcoplasm, C. Summation of the stimuli, D. "Beneficial effect"', 'role': 'user'}, {'content': 'Answer: B \nExplanation: "Tetanizing stimulus" means high-frequency stimulation. When stimuli are applied in quick succession, there is release of Ca++, with each stimulus, from the SR into the sarcoplasm. For the muscle to relax, this Ca++ should be pumped back into the SR, which fails to happen due to the rapid succession of stimuli. The muscle remains in a sustained state of contraction, called as "tetanus".', 'role': 'assistant'}]