Dear Aspirant,

You can appear UPSC CSE exam after graduation. The minimum eligibility of UPSC CSE is you have to be a graduate student to apply for the exam. You can choose B.SC  if your interest is in science subjects or the best option ,I think is choose B.TECH because while giving the interview the interviewees will prefer technical students upon general studies students. Choosing B.TECH can have backup plan also.

For more information on UPSC CSE check this link:- https://competition.careers360.com/exams/upsc-civil-services-exam/articles

Hope this helps.

Good Luck!