According to the passage, a competent baby-sitter should be able to__________ .

C
细节推断题。由文章第二段第四句“In addition，she should be able to handle any unexpected emergency with common sense and be calm at all times．”(她得知道如何运用常识处理突发状况并且随时保持冷静。)可知C项正确，其余各项文中均未提及。