Pointing to a man, Roshani said that his wife is the only daughter-in-law of my father-in-law Mohan. How is the man related to Mohan?

Let's break down this blood relation puzzle step-by-step!

Roshani's statement is the key: "His wife is the only daughter-in-law of my father-in-law Mohan."

First, consider "Roshani's father-in-law Mohan". This means Mohan is the father of Roshani's husband.

Then, "the only daughter-in-law of Mohan" means the *only* wife of Mohan's son (or sons). Since Roshani is married to Mohan's son, Roshani herself must be that only daughter-in-law.

So, the man's wife is Roshani. This means the man is Roshani's husband.

Since Roshani's husband is Mohan's son, it follows that the man is Mohan's son.

Therefore, the correct answer is: Son