\( \mathrm{pH} \) of a saturated solution of \( \mathrm{Ca}(\mathrm{OH})_{2} \) is 9 . The solub...

\( \mathrm{pH} \) of a saturated solution of \( \mathrm{Ca}(\mathrm{OH})_{2} \) is 9 . The solubility product \( \left(K_{s p}\right) \) of \( \mathrm{Ca}(\mathrm{OH})_{2} \) is :
[NEET 2019]
(a) \( 0.5 \times 10^{-10} \)
(b) \( 0.5 \times 10^{-15} \)
(c) \( 0.25 \times 10^{-10} \)
(d) \( 0.125 \times 10^{-15} \)