Proper onsite SEO for Local/National business

I have a web customer that runs a trade school. They offer:
1) Local classroom in-person classes in San Diego
2) Local classroom classes in Phoenix
3) Online classes via the internet, where anyone anywhere in the US could take the class online.
For ONSITE SEO purposes, I am wondering what the best site(s) layout should be, meaning:
A) One Website, offering all 3 types of the above class offerings in 3 different 'silos' within the one site ...
  OR
B) One Website, using 3 SubDomains or SubFolders, one for each type of class (I seem to remember that Google loved subdomains ... or was it subfolders? Not sure if that is still google-relevant)
  OR
C) Do 3 different distinct unique Websites (not duplicates) using 3 Unique URLs, in order to specialize, and in order to use Google Local/Business that targets just 1 location each
  OR
???