When solid lead iodide is added to water, the equilibrium concentration of $I^-$ becomes $2.6 \times 10^{-3}$M. What is the $K_{sp}$ for $PbI_2$

Question

(a) $2.2 \times 10^{-9}$

(b) $8.8 \times 10^{-9}$

(c) $1.8 \times 10^{-8}$

(d) $3.5 \times 10^{-8}$