The correct option is A SRPQ
The sentence has two clauses. In first clause, P is the first part of the subordinate clause, and Q the second. In the dominant second clause, S is the verb and R direct object. Hence, the structure should be SRPQ and Option B, that is "My father paid John's fees when he was at school last year." is correct. The rest of the options do not adhere to this rule, hence incorrect.