A girl introduces a boy as 'son of the daughter of the father of her uncle'.
How is the boy related?
I. Brother
II. Son
III. Uncle
IV. Son-in-law

Question: 以下哪项是正确的？
Options:
A. 仅 IV, B. I 为真, C. 以上各项均不成立, D. 仅 III
Answer: B
True statement: I