She asked (A) why (B) did Mark look (C) so embarrassed when he
Giải thích
Đáp án B
Cấu trúc: S + asked + WH- + S + V (lùi thì).... (câu hỏi tường thuật)
E.g: “Why did you come back late?” my mother asked
=> My mother asked why I had come back late.
Đáp án B (did Mark look => Mark looked)