Find the radius and center of the sphere. ( x² + y² + z² - 8x - 4y - 4z = -20 )
a) Radius: 5, Center: (4, 2, 2)
b) Radius: 4, Center: (-2, -2, -2)
c) Radius: 3, Center: (2, 2, 2)
d) Radius: 2, Center: (-4, -4, -4)