Access parent property name from child class

I have a classes like:

class A {
    public B prop1 {get; set;}
    public B prop2 {get; set;}
}

class B {
    public B {
        // which name of my parent property - prop1 or prop2?
    }
}

How can I find out from the constructor of class B: the value of which of the properties of the parent class (prop1 or prop2) this instance of class B is?