AOA.....please guide me on selecting optional subjects i want to opt IR, history of USA, International Law and physics but i am not sure about physics...???.......i have interest in physics; i had physics in fsc but didnt study it after that i love studying theory of relativity, quantum mechanics and other interesting topics related to physics but em not sure what the real requirements of css paper are....so what should i do.....how much time will it require to prepare it and what are the best books for preparation of physics..
and as we give css after bachelors, are they going to give questions of bachelors level or they can give phd level questions too ?....moreover if you think opting physics is a bad idea then what else should i opt