Straight to CC or CS?

I am a high school senior and I got accepted to CSUCI. I was planning on going there and majoring in biology and get my Bachelors there and then transfer to UCB or UCSB. I heard it’s easier to get accepted to a UC if you are a CC student, so what is my best option? Is it better to attend a CS first or a CC? What is my best option economically as well as for my future?

You seem kinda confused here. If you get your bachelors then your CC student days were long in your past because you had to go to a 4-year college to get a bachelor degree. After you get a bachelor you do not “transfer” anywhere. You apply for a grad program. And nobody in a grad program cares if you went to a CC at some point in the past, your most recent school is what matters.

If you want to transfer to UCB or UCSB and finish your bachelor’s, then I would highly recommend attending a community college for 2 years and then transferring. A CCC to UC is easier than a CSU to UC transfer since CSU courses do not always articulate well with the UC courses needed for transfer. If you want to go to these UC’s for Grad school, then @mikemac’s explanation above is what you need to know.