Pointing to Gopi, Nalni says, “I am the daughter of the only son of his grandfather.” How Nalni is related to Gopi?

The correct answer is A. Niece.

Gopi’s grandfather has only one son, and Nalni is the daughter of that son. This means that Nalni is Gopi’s niece.

Option B is incorrect because Nalni is not Gopi’s daughter. Option C is incorrect because Nalni is not Gopi’s sister. Option D is incorrect because Nalni’s relationship to Gopi can be determined.