I will start by explaining my scenario in code:
public class A { } public class B : A { } public class C : B { } public class D { } public c
typeof(B).IsInstanceOfType(c)
Similar to the answer above from sam-harwell, sometimes you may have the type "B" in a variable, so you need to use reflection rather than the "is" operator.
I used Sam's solution, and was pleasantly surprised when Resharper made this suggestion.