If (G, .) is a group such that (ab)- 1 = a-1b-1, ∀ a, b ∈ G, then G is a/an

If (G, .) is a group such that (ab)- 1 = a-1b-1, ∀ a, b ∈ G, th

1.	If (G, .) is a group such that (ab)- 1 = a-1b-1, ∀ a, b ∈ G, then G is a/an
A.	commutative semi group
B.	non-abelian group
C.	abelian group
D.	None of these
Answer» D. None of these