Hello,Civil service exam is known for its unpredictability. There is no observed trend that student choosing a certain optional or from a specific profession clearing the exam.Since all the subjects' knowledge are being tested in the exam process it is better that you select a subject of choice from the  optional subjects and can pursue a degree in it.Of course it wont offer an edge but you can find the preparation from those subjects relatively easy.People usually choose degree in Histroy,Agriculture,English to help their preparation.

Hope this helps.

Hi

One can choose any subject or course  of his or her choice based on your interest for graduation

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, but yes  if  you are asking a degree course which can help in your UPSC preparation then choose BA or Arts

As

choosing Arts or the humanities 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.

Thankyou