Fill in the blank with a suitable preposition.
He had a photo of his family _______ the desk.
The prepositions ‘on’ and ‘upon’ mean to place something over a surface. But ‘on’ is used to denote an object being placed on an inanimate surface while ‘upon’ means to climb on a moving object or thing. In the sentence, the desk is a surface ‘on’ which something is placed and not a moving object. Hence option A is correct, while option B is incorrect. On the other hand ‘of’ signifies belonging which is not the case here. The photo of his family doesn’t belong to the desk or originates from it. Thus option C is incorrect. Similarly ‘for’ is used to refer to the person/thing that something is intended for. The photo is not placed for the sake of the desk. Hence option D is incorrect.