Do the UC's participate in score choice?

I think I understand but just to make sure – I’m applying to Berkeley and UCLA, and on the application, it says to self report only your highest scores, yet the website says:
“In the College Board’s Score Choice module, ensure that all scores are sent to UC. We require all scores and will use the highest scores from a single administration.”

So, I have to send them all scores from all sittings, but only self-report my highest scores in the application?

yes. Send all scores, self report the single-sitting highest scores you have.

No, the UC’s do not participate in Score Choice. You need to send all scores even if reporting highest score on the application.

You don’t have to send all subject tests, since they are only recommended.

So since subject tests are recommended but not required, I don’t have to send/report them all? Just all SAT/ACT sittings?

I’ve seen others say this as well, but I’m not positive about it because with Georgetown all subject test scores had to be sent even though they were just “strongly recommended”

It depends upon the school. You need to check each school’s requirements.