Write x² + y² + z² - 2x - 4y - 4z = 16 in standard form.
a) (x-1)² + (y-2)² + (z-2)² = 9
b) (x-1)² + (y-2)² + (z-2)² = 25
c) (x-2)² + (y-2)² + (z-2)² = 16
d) (x-2)² + (y-4)² + (z-4)² = 36