What determines the Class A,B,C,D?

[Justin Young]

Aloha BP!

Listening to Jake and Gino's podcast yesterday, they were discussing owning properties that are Class B+ to C+ and why they pick those type of properties. My question is what determines the different classes? I would assume that Class A is a top notch property with top of line tenants but lower cash flow because you're giving that up for a premium property/tenant. Not sure if that's correct but how would one define the fine line between C+ and say B-? It seems like a very small margin.

Thank you all in advance, ALOHA!