Pointing to a boy in a photograph, Akhil says, "He is the

Pointing to a boy in a photograph, Akhil says, "He is the son of my mother's only son." How is Akhil related to that boy?

Photograph is the son of Akhil’s mother’s only son.
or, Photograph is the son of Akhil.
or, Akhil is the father of the boy.