Hey Nidhi!

You can check your application form or DU undergraduate registeration form, that you filled and must have downloaded during registration, there you will get to see your preference subjects. In case you want to apply for any course, you have to check the eligibility criteria of a particular subject and eligibility percentage of a college for a particular course, it does not matter whether you have chosen that course for preference or not meaning even if the course you want to apply in hasn't been selected by you in your preference subjects then also you may still apply for it. If you have more doubts, you may write in the comment section.