问题补充：
---book is this?
--- I think it Carla’s. It has his name on it.
A. Who is, could be
B. Who’s, might belong to
C. Whose, must be
D. Whose, can’t belong to
答案：
A. Who is, could be
B. Who’s, might belong to
(答案→)C. Whose, must be
D. Whose, can’t belong to
解析：whose 表示谁的，作为定语，根据后文内容It has his name on it.，可知答案为C，表示非常肯定的推测。故选C
