Hi Nida,

The UPSC examination is held for jobs inn the Indian Administrative Sector. For eligibility to  the examination, you need to have a Bachelor's Degree from a recognized Board or University. It is not mentioned what field it needs to be in, so you can go for any field of your preference.

As you have taken Science in your 10+2, you can go for Engineering(If you have Math), Medical(If you have Biology), Law, Humanities, Agriculture, etc. Honestly, no one can really tell you which field would be the best for you. That is a decision you should make.

Regardless, you should start researching History and keeping track of Current and World affairs as it will help you a lot for your UPSC journey.