UC Application a-g?

I’m a little confused as to what the UC app means by a-g courses. I read their website, but I have a few questions.
What about Psychology? I’m taking Psychology but it’s not in any of their drop-down menus when I’m selecting my courses.
What about Multimedia?

This is the requirements page

http://admission.universityofcalifornia.edu/freshman/requirements/

What exactly is a College-Prep Course that is the “g” category?

For my son’s HS (California), Psychology is listed on category “g” college prep. If you attend a California HS, you can look up your HS courses on the following link and see which courses fit in each category. If not a California HS student, then you can email UC admissions or try and figure out what would be the appropriate category based on the a-g course descriptions.

https://hs-articulation.ucop.edu/agcourselist/#/list/search/all

Is Multi-media considered an art or visual art class? If so, put under “f” for VPA.

The “g” category can be fulfilled by an additional course from the “a” through “f” categories (e.g. an English, math, history, science, foreign language, or art course beyond the minimum required), or other courses specifically listed as being applicable only to the “g” category.