D.(x,y-3)
Because x basically represents the horizontal and y represents vertical
Answer:
which is Choice A
=========================================
Work Shown:
Let 
So,

This therefore means:

as long is x is nonnegative.
Hi
area of circle, which is call in proper math terme circumference ( latin for going around) is given by this formula :
2 times radius x pi
As math is all about knowing your formula and training, I let you have a shot. You wont progress other wise.
Ask in comment section if you are still blocked.