If 'a' and 'b' are two whole numbers, then under what condition is the commutative law applicable to subtraction?

If 'a' and 'b' are two whole numbers, then under what condition is the

1.	If 'a' and 'b' are two whole numbers, then under what condition is the commutative law applicable to subtraction?
A.	\[\text{a=b}\]
B.	\[\text{a}\ne \text{b}\]
C.	\[\text{ab}\]
D.	\[\text{ab}\]
Answer» B. \[\text{a}\ne \text{b}\]