Dear Student,

It is all up to you. What you enjoy learning about and is most interesting to you.

Moreover BSc will only help if you take a science  subject as your optional.

Bsc computer science- Because programming is so rigorous, if you decide to study computer science, I think your analytical and logical skills will have much improved.  I think you would have to pick a topic that has a strong scientific component. You can choose from a variety of areas, such as geography, anthropology, geology, math, physics, psychology, and others, based on your interest in them and the resources that are available.

Bsc microbiology- The UPSC optionals always have a curriculum available. Students having a background in microbiology might prepare for the upcoming UPSC exam by choosing a topic in the medical sciences, anthropology, or even zoology.

But remember, All graduate students must take the ias prelimbs test. For the mains exam, students can select two subjects, however they must complete those two subjects for their graduate degree.

According to that, prepare for the exams.

All the best.