Hi,

UPSC syllabus is basically a combination of all the subjects and does not focus on any particular stream, thus, it does not matter much which stream you choose. To be eligible for UPSC examination, you must have cleared your graduation with any discipline. You can choose any stream in class 11th and 12th.

You can refer to this link for more details: https://competition.careers360.com/exams/upsc-civil-services-exam#date_blocks

I hope this helped you.