ANSWER
D. (x - 2)² + (y - 6)² = 16
Step-by-step explanation
The equation of a circle in standard form is,

Where r is the radius and (h, k) is the center of the circle.
In this case, we have a circle with center at (2, 6) and radius of 4, so the equation is,

Hence, the equation of the circle is (x - 2)² + (y - 6)² = 16.