Pointing to a man standing in front of Mohan, Mohan said, "He is the father of my mother's daughter, his daughter is the granddaughter of my grandfather." How is that man related to Mohan?

Let's break down the quote by Mohan step-by-step:"my mother's daughter" $\to$ Mohan's sister."the father of my mother's daughter" $\to$ The father of Mohan's sister, which means he is Mohan's father.Let's check the second part: "his daughter (Mohan's sister) is the granddaughter of my grandfather." This perfectly matches the paternal family structure. Therefore, the man is Mohan's Father.