What is the minimum number of moles of Pb(NO₃)² that must be added to 0.10 L of a solution that is 1.0 M in MgCl₂ and 1.0 M in KCl in order to precipitate all the chloride ions?
a. 0.05 mol
b. 0.10 mol
c. 0.20 mol
d. 0.40 mol