单选题 Meeting my first teacher of English after all these years was an unforgettable moment, ______ I will always treasure.
A. that B. one C. it D. what

【正确答案】 B
【答案解析】[解析] 由横线前的逗号可知后半句为由which引导的非限定性定语从句,或由one指代,构成同位语从句。