Hi

You can choose any subject or course  of your choice based on your interest for your graduation after your 12th for UPSC

This is because,

to be eligible for UPSC  examination there is no compulsion to be a graduate in a particular subject, all you need to be eligible is that you should be a graduate in any discipline

So you can choose any stream of your interest after your 12th PCM like Btech etc, the additional benefit of courses like Btech is that you will have have a plan B i. e a good back up  if you fail to clear UPSC in the worst case , but yes when it comes to UPSC then if you choose BA or Arts

then

choosing Arts can be really helpful for your UPSC  examination, this is because in Arts you will be learning subjects like history , polity etc which are a part of the UPSC syllabus so it will help you in your upsc examination

So, take your time and decide.

To help you further ,

here's a brief of your UPSC exam pattern :-

UPSC civil services examination has 3 stages listed below :-

• Prelims exam :- it is objective paper and is of qualifying nature , there are 2 papers in prelims
• Mains exam. :- it is descriptive /written examination . There are a total of 9 papers in Mains examination
• Interview :- After qualifying mains, you have to go through interview round, and it is more of test of your personality rather than knowledge.

To know exam pattern in detail visit :- https://competition.careers360.com/articles/upsc

Thank you