UPPSC Exam.
It is not like picking a flower from a bouquet, so certain things should be thought before choosing an optional for UPSC.
From Most Important to Least Important order :
1. Love and Interest towards Subject
2. Suites your personality (you are good with theory type or practical type subject)
3. Availability of material on Internet and in Market.
4. Success Rate of The Subject
5. Available good coaching institutes (if you prefer coaching than self study)