C and D
D is the exact same.
For C this is already proven but you can test this by choosing any number for K (4) and multiply it by 1/2. You get 2 which is the same as 4/2.
C) 1/2 k
If you Put any value times 1/2 it puts that number over top see:
5(1/2) = 5/2
7(1/2) = 7/2
So if you do k(1/2) = k/2
Answer D is the same as the equation we are looking for.
tube or goog would be a great resource to with that question