I know Ross mentions the basic science being either 4 or 5 semesters. Is this really an "option" or do they make everyone do 5 semesters for $$?
It's absolutely an option. X is accelerated 4 semesters, traditional is 5. You have a choice after 1st semester. They may recommend traditional if you struggled with 1st but that's not a requirement as far as I know.