According to their website, RCC "offer(s) workshops bi-weekly that explain eligibility requirements and the selection process." You should attend one of those workshops and bring a copy of Mt SAC's catalog (a schedule will work if you don't want to buy a catalog) so you can ask which classes at Mt. SAC meet their pre-requisite criteria.
Anatomy, Physiology, and Microbiology are the main pre-requisites for every nursing school
and the ones you should be most concerned about. Mt SAC offers two different classes for each of the three. ANAT 10A, ANAT10B and MICR22 are the 4 unit classes for Anatomy, Physiology, and Microbiology respectively. ANAT35, ANAT36, and MICR1 are the 5 unit options for those same classes. Some nursing schools
in the area will accept the 4 unit classes, others will only accept the 5 unit classes. To be safe, take ANAT35, ANAT36, and MICR1 so you can be eligible to apply to as many programs as possible should you not get into RCC.