Which of the following is the equation of a circle with center (5, -2) and a radius of 3?
a. (x - 5)^2 + (y +2) ^2 = 9
b. (x + 5) ^2 + (y - 2) ^2 = 9
c. (x - 5)^2 + (y + 2) ^2 = 3
d. (x + 5) ^2 + (y - 2)^2 =3