B.Sc

Hi,
You should mention your stream. Well, as you didn't mention it, I can't give you the appropriate answer, but for better placements, you can opt for M.Sc, PG Diploma, M.Sc with training, PG Diploma with any other short-term course related to your stream.

Hi,
The best colleges for your course are:
CMC (Christian Medical College)
JIPMER
JSS University
According to me, JIPMER is the best because of ranking, less fee structure and the medical facility.
I hope you got your answer.

There are enormous fields like astronomy, astrobiology, astrochemistry, astromaths, clinical psychology marine science and many more. It totally depends on your interest.

Dear Preeti,
To be honest, 51% is not really good for you if you want a boom in your career so firstly focus on scoring more. Now come on to your question, best option for you is M.Sc in your desired field after having some experience. But if you don't want to go for M.Sc then you may opt for MBA.

You need to score above 95% in HSC.

Yes, B.Sc (Hons) in agriculture has a very bright future.