Agriculture

I am a student of Atarra. How can I join Bundelkhand University, Jhansi for B.Sc agriculture.

Hi, CAT has not field. Common Admission Test (CAT) is national-level management entrance examination conducted by the Indian Institutes of Management (IIM). Apart from 20 Iims, CAT scores are used for admission to various management institutes across the country.
https://www.shiksha.com/mba/exams/cat

Each has comparable scope. However, all three fields are very different from each other and you should pursue a course which you feel comfortable studying, and where your interests lie. Starting salaries for each of these fields may vary as they entail working for three different industries. Good luck!

So, you can pursue MBBS, BAMS, etc.

In order to pursue a science course at any of these colleges, you will have to appear for an entrance. In this article, we have listed some popular B.Sc and M.Sc entrance exams that science aspirants should consider giving in order to secure admission in a good college. Refer to the article mentioned at the link provided below for a detailed list of entrance exams for B.Sc courses.
https://www.shiksha.com/science/articles/top-bsc-msc-entrance-exams-in-india-blogId-13484