Answer:
B. -a+b
Explanation:
You want the additive inverse of a-b.
Additive inverse
The additive inverse of an expression is the value gives zero when summed with the expression.
If we call the additive inverse 'q', then ...
(a -b) +q = 0
Subtracting (a -b) gives ...
(a -b) +q -(a -b) = -(a -b) . . . . indicate the subtraction
q = -(a -b) . . . . . . . . . . collect terms
q = -a +b . . . . . . eliminate parentheses
The additive inverse of a-b is -a+b.
__
Additional comment
The commutative property of addition lets us write that additive inverse as b-a.
The additive inverse is also known as the "opposite." It can be found by multiplying an expression by -1 (or subtracting it from zero, as above).