In order to find the equation that represents this boundary, let's use the equation of the circumference below:
Where r is the radius and the center of the circumference is the point (h, k).
Looking at the image, we can see that the circumference is centered at (-6, -1), and its radius is equal 4 units.
So we can write the following equation, using h = -6, k = -1 and r = 4:
Therefore the correct option is the second one.