How do I check if a derived class is a certain class?

For example,

I have ScriptableObject A and then 3derived class A1 A2 A3

There is also Runtime Class B and derived from it, B1 and B2

B1 can only use A1 and A3 B2 can only use A2

And finally, there is manager Class C

Class C can only call function from base class B, But the said function can received any version of classA

As such, class B1 and B2 have a need to check which kind of A they are receiving.

public class B1 { void Update() { if( A is not A1 or A2 ) return; }

}