This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Drugs, Subject name: Medicine
[{'content': 'Which of the following is selective myosin activator? \nSelect and explain. \nA. Istaroxime, B. Omecamtiv & Mecarbil, C. Tolvaptan, D. Levosimendan', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B. Omecamtiv & MecarbilThese are selective Myosin activator. They prolong the ejection period and increases fractional shortening.', 'role': 'assistant'}]