Dear All

I encounterd a quetion related type casting.
Question is

class class1{}
class class2 extends class1{}
class class3 extends class3{}

A. class3’s parent class is class2, and class2’s parent class is class1.
B. class3’s parent class is class2, class2’s parent class is class1, and class1’s parent is Object.
C. class1’s parent class is class2, and class2’s parent class is class3.
D. class1’s parent class is class2, class2’s parent class is class3, and class3’s parent is Object.

Answer is A , but i don't know how (A) is correct

If any one know please explain me.