@soojin1 really? You keep asking these same questions over and over, plus other basic questions that can easily be found if you go to assist or do a google search. We’re here to help, but really, we’re not people’s servants doing all their research for them. I don’t mean to be harsh, but I’ve answered about five of your very basic questions - questions that clearly illustrate you didn’t even bother to do a basic search of your major. 
Since the UCs are research institutes, now’s a good time to get your feet wet. 
We’re here for lots of answers, but come at least somewhat prepared, please.