You should decide yourself what do you want to do as per your interest, If you are interested for Engineering programme then you can go for BE/ B.tech programme, JEE Main is the National level Exam for the admission to engineering programme in NITs, IIITs, GFTIs. As you told that you belong to Bihar then you can apply for Bihar State level Engineering Exam BCECE Entrance Exam.

Besides Engineering Aspirants you can pursue Defence Services through NDA which requires Mathematics in Class 12. You can also go for Bachelor of Science in specializations under the pure sciences domain such as Maths, Physics, Chemistry, Botany, Zoology etc.

If you are interested for Management, Commerce or Law programme then you can go for BBA, B.com, B.A LLB etc.

You can choose any of the option as per your interest.

Good Luck!