The correct option is A a−b
Since, a36−b36
=(a18)2−(b18)2 [∵a2−b2=(a−b)(a+b)]
=(a18−b18)(a18+b18)
=[(a9)2−(b9)2](a18+b18)
=(a9−b9)(a9+b9)(a18+b18)
=[(a3)3−(b3)3](a9+b9)(a18+b18) [∵a3−b3=(a−b)(a2+b2+ab)]
=(a3−b3)(a6+b6+a3b3)(a9+b9)(a18+b18)
=(a−b)(a2+b2+ab)(a6+b6+a3b3)(a9+b9)(a18+b18)
Option A is correct.