Psychology

You can go for CA, as it is one of the most prominent course for commerce students.

With commerce background, you would not be deemed eligible for B.Sc psychology. For B.Sc psychology, you need to have studied general mathematics/ biology/ zoology/ psychology/ sociology/ advanced English as the subject.

The difference between MA and M.Sc in Psychology is not much. But it will differ according to the university/college offering you the same. Talking generally about MA offered in India by some top universities like Delhi University, Jamia Millia Islamia, Ambedkar University, etc., has a different approach and a combination of all subjects whereas M.Sc offered by BHU, Allahabad University, etc., focuses more on cognitive aspect of it. But, if we say what would be best to choose, it will not matter if your interest lies primarily in psychology.

There are English Paper-1 and English Paper-II in the course structure of B.Sc psychology. To apply B.Sc in psychology you need to have passed 10+2 examination or three-year Diploma.
For course structure, refer to the link: https://www.shiksha.com/humanities-social-sciences/psychology/course/b-sc-in-psychology-alagappa-university-distance-education-karaikudi-81689

For admission in MA psychology, you need to have passed graduation in relevant stream. You can apply directly to the college and thereafter you be called for an interview.