Pointing to a boy,Seema said,"He is the son of my grandfather's only child". How is the boy related to Seema?

$A$ woman introduces a man as the son of the brother of her mother. How is the man related to the woman?

Pointing to a photograph,Vipul said,"She is the daughter of my grandfather's only son." How is Vipul related to the girl in the photograph?

Anil introduces Rohit as the son of the only brother of his father's wife. How is Rohit related to Anil?

$K$ is the brother of $N$ and $X$. $Y$ is the mother of $N$ and $Z$ is the father of $K$. Which of the following statements is not definitely true?

Deepak said to Nitin,"That boy playing with the football is the younger of the two brothers of the daughter of my father's wife." How is the boy playing football related to Deepak?