Science

Please refer to the link provided below for career options after completing a course in B.Sc. in Mass communication:
https://www.shiksha.com/mass-communication-media/articles/your-career-after-mass-communication-studies-blogId-4624

Courses you can take up after board exams (10+2):
1) B.Sc.
2) B.A (Pass/Honors)
3) BCA
4) BBA
5) B.Com (Pass/Honors)
There are many other courses as well. I am only mentioning the popular courses taken up by students after their board exams.

Course you can do after B.Sc:
1) MBA
2) M.Sc
3) MCA
4) Defence Service (CDS)
5) Civil Services (UPSC)

Switching from a regular to correspondence course might not be permitted. You may have to quit your B.Sc. course from DU and then take up a correspondence course starting from first year. If you have been selected in the Navy, I would advise you to prepare for starting with them.

Please refer to the article with the link mentioned below for career prospects after completing M.Sc:
https://www.shiksha.com/science/articles/what-is-msc-course-all-about-know-the-full-form-eligibility-scope-blogId-13439

Complete your course in B.Sc agriculture, and then consider getting admission in an M.Sc course in India or abroad. Getting admission in an M.Sc course depends on your performance in your undergraduate field of study, so do well in B.Sc and then consider opting for an M.Sc course.

Please visit the page with the link mentioned below for full details on scope of entering the science field:
https://www.shiksha.com/science/articles/what-is-bsc-course-all-about-know-the-full-form-eligibility-scope-blogId-13262

Please refer to the link provided below for a list of colleges offering M.Sc courses in India:
https://www.shiksha.com/science/colleges/m-sc-colleges-india