I would suggest getting educated in btech as it provides atleast some technical knowledge, but if youre totaly against it thats completely fine.

Having said that, if you have a strong interest in a particular field (be it BA or B Sc), you can opt for that. The UPSC does not discriminate based on the nomenclature of your degree, 

Hello anamika

Firstly congratulations on achieving such great score in pcm .

Answering your question Yes of course BA is an excellent option if you are planning to go for civil service examination. You can surely take this course. All the best for your future academic endeavor.