Mark the letter A, B, C, or D on your answer sheet...

Câu hỏi: Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions.
What happened in that city were a reaction from city workers, including firemen and policemen who had been laid off from their jobs.

A. What happened

B. Were

C. Including

D. Their