What Is the Minimum Concentration of Cu²⁺ Required to Begin $\times$

What is the minimum concentration of Cu²⁺ required to begin precipitating Cu(OH) ₂(s) in a solution buffered at pH 10.63? The K_sp of Cu(OH) ₂ is 2.6 $\times$ 10^-19 and K_w = 1.01 $\times$ 10^-14.

A) 2.1 $\times$ 10^-4 M
B) 1.1 $\times$ 10^-8 M
C) 6.1 $\times$ 10^-16 M
D) 1.4 $\times$ 10^-12 M
E) 2.3 $\times$ 10^-21 M