Identify the underlined word/ phrase (A or B, C, D...

Câu hỏi: Identify the underlined word/ phrase (A or B, C, D) need correcting to become an exact one: I met (A) a lot of interesting (B) people while (C) I was studying at (D) Ho Chi Minh City.

A. met

B. interesting

C. while

D. at