SORRY...按错了~

题目

SORRY...按错了~
Meeting my uncle after all these years was an unforgettable moment,____I will always treasure.
A.that
B.one
C.it
D.what
D怎么不对呢?

答案

题目也没有哦.
我觉得是选B,楼上的,我们可以讨论一下,这题其实蛮怪的,个人觉得one做moment 的同位语,后面that省去,原句应为one that i'll always treasure.
如果作为定语从句的话,what肯定不对,但也应该前面也没有出现需要用that的情况