Mark the letter A, B, C, or D to indicate the sentence that is combined from two following sentences.Câu hỏi He answers all questions about President Ho Chi Minh. No one can do that. A. He is the only person to answer all questions about President Ho Chi Minh. B. He is the only person answered all questions about President Ho Chi Minh. C. He was the only person to answer all questions about President Ho Chi Minh. D. He is the only person answering all questions about President Ho Chi Minh.