pH of a saturated solution of $Ba(OH)_2 $ is 12. The value of solubility product $(K_{SP}) of Ba(OH)_2$ is

Question

( A ) $4.0\times10^{-6}$
( B ) $5.0\times10^{-6}$
( C ) $5.0\times10^{-7}$
( D ) $3.3\times10^{-7}$