d
Step-by-step explanation:
first do the x, you see x^2-8x so you first want to do (x-4)^2. But then you will see we have created an +16 so wee -16 and then we get (x-4)^2+y^2-9. There is no y to the first power term, therefore you choose d after moving 9 to the Right hand side.
