Inheritance

I can not understand the inheritance syntax of question number 11 in diagnostic exam, which declares-

class C extends A.B

We cannot extend more than one class in java, then what does this syntax means. Please solve my confusion.

Thank you.

Class B is a static nested class of the outer class A. When we say A.B, we refer that static class B which exists inside the class A. So in the inheritance part here, we are only extending B - not A.