look at the colleges you want to go to and the exam boards they use for both those subjects because different exam boards may cover slightly different content. for each subject, look at what do you study in them, how are the exams structured etc. don't just pick a subject because you think you have to, pick it if you have a genuine passion for it.
when i was researching what subjects to take for medicine, i realised that i only needed chemistry and one other science, plus a subject of my choice. i chose english literature and it was one of the best decisions i've made. i can't help you pick a subject because i don't know you - what you like/dislike, how you study, what your interests are. that's something that you need to decide so make it carefully and consider all your options.
(there is almost always the option to transfer courses once you get to college but you don't want to waste precious days waiting for timetables to be rearranged, so just make an informed decision early and only do that if you feel like you absolutely have to)