Why is this? Recall that (x-h)^2+(y-k)^2 = r^2 is the general template of a circle. The center being (h,k) and the radius is r.
For the equation (x-4)^2+(y+2)^2 = 16, we have a center of (4,-2) and radius 4. Note that 4^2 = 16.
The graph of choice G shows these properties so that's why it's the answer. Keep in mind that each tickmark represents 2 units. Choice I is close since the center is correct but the radius is too small.