ACT Practice Question: Circles in Coordinate Geometry

 
Here is a practice question on how the equation of a circle in the coordinate plane is related to the coordinates of its center and radius.

In the standard $(x, y)$ plane, a circle has a center at $(2, -3)$ and a circumference of $8\pi$. Which of the following is an equation for this circle?

1. $\quad (x-2)^2 + (y-3)^2 = 16$
2. $\quad (x+2)^2 + (y-3)^2 = 16$
3. $\quad (x-2)^2 + (y+3)^2 = 16$
4. $\quad (x+2)^2 + (y-3)^2 = 64$
5. $\quad (x-2)^2 + (y+3)^2 = 64$