At a Particular Temperature, the Hydroxide Ion Concentration in a Saturated

At a particular temperature, the hydroxide ion concentration in a saturated solution of Ni(OH) ₂ is 2.2×10 ^{- 6} M . What is the K _sp of Ni(OH) ₂?

A) 8.9×10 ^{- 42}
B) 4.1×10 ^{- 27}
C) 2.56×10 ^{- 18}
D) 1.6×10 ^{- 9}
E) 5.3×10 ^{- 18}