If this dictionary is not yours , ____ can it be ? 选择题?

题目

If this dictionary is not yours , ____ can it be ? 选择题?
If this dictionary is not yours , ____ can it be ?
A:what else B:who else C:which else's D:who else's
答案是D 为什么? 怎么翻译?

答案

如果这本字典不是你的,那么它还会是谁的呢?