THE WORD "THEY" IN THE 2ND PARAGRAPH REFERS TO A. EFFORTS...

23. - DE THI THU THPT QUOC GIA NAM 2017 MON TIENG ANH TRUONG THPT QUANG XUONG 1 THANH HOA LAN 1 CO DAP AN
Tiếng Anh DE THI THU THPT QUOC GIA NAM 2017 MON TIENG ANH TRUONG THPT QUANG XUONG 1 THANH HOA LAN 1 CO DAP AN

23. The word "they" in the 2

nd

paragraph refers to

A. efforts B. sources C. counterparts D. authors