Which of the following is a result of shifting a circle with equation (x - 5)^2 + (y - 6)^2 = 36 to the right 2 units?
a. both the x- and y-coordinates of the center of the circle decrease by 2.
b. the y-coordinate of the center of the circle increases by 2.
c. the x-coordinate of the center of the circle increases by 2.
d. both the x- and y-coordinates of the center of the circle increase by 2.