Using the following equation, find the center and radius:
x²+4x+y²-6y=-4
a. The center is located at (2, -3), and the radius is 3.
b. The center is located at (-2, 3), and the radius is 9.
c. The center is located at (2,-3), and the radius is 9.
d. The center is located at (-2, 3), and the radius is 3.