Answer:
B
Explanation:
f(x) can be factored from f(x) = 3x-6 into f(x) = 3(x-2). Divide f by g in a fraction now.

Since anything divided by itself is 1 then x-2 divided by x-2 is 1 leaving 3 as the answer. This leaves a or b. The answer is b because the division cannot happen if the denominator is 0. So x-2 cannot ever be 0. It's 0 when x=2. The answer is b.