We have to draw a family tree and find the relationship between Anita and Prabhu.Consider the following family chart:The final family tree will be:Prabhu's father means there is a generation gap of 1.Anita says Prabhu's father is the only son of my father this means Anita and Prabhu's Father must be of the same generation.Thus this is clear that Anita can be either Aunty or Uncle of Prabhu. As Uncle is not there in the option this means Anita is Aunt,As it can be seen that Anita is her Aunt of Prabhu.Therefore, the correct answer should be "Option1: Aunt".