We want to know which equation is most likely represented by the circle graphed.
For doing so, we remember the general equation of a circle:
In the equation, (h,k) is the center of the circle, and r is the radius. Thus, if we obtain the center and the radius of the circle, we will be able to obtain its equation. The center is on the point (-1, -6), as we see on the figure:
And the radius (the distance from the center to a point of the circle) is 4:
Replacing on the formula, we obtain that the equation that represents the circle graphed is: