See the subject you are doing graduation on doesn't matter for UPSC. The only thing which matters regarding the selection in UPSC CSE & becoming an IAS is the preparation you have gone through. So you have to make your preparation great. Now you should choose the subject of graduation which you are interested. Pursue that subject. The core psychology behind this is that, if you study the subject of your interest, then it will require less time for you to invest in your studies & you can invest more time in your preparation.

The subjects you have in 10+2 are quite good and if you wish you can do the UG program in Psychology, Economics, or Political Science. This subjects are in the curriculum of UPSC and having an indepth knowledge may provide you a better platform. Now its your choice, the thing you should understand is that your preparation matters & not your graduation subject.

For more information regarding UPSC CSE preparation consider the link provided below:

https://competition.careers360.com/articles/how-prepare-for-upsc-ias

I hope this helps. Wish you a great eve!