What Is the Ksp for Magnesium Hydroxide,Mg(OH)2,if the Hydroxide Ion

What is the Ksp for magnesium hydroxide,Mg(OH) 2,if the hydroxide ion concentration in a saturated solution is 0.00016 M?

A) Ksp = 1.3 x 10-8
B) Ksp = 2.6 x 10-8
C) Ksp = 2.0 x 10-12
D) Ksp = 4.1 x 10-12
E) Ksp = 8.2 x 10-12