A Solution Is 0

A solution is 0.100 M in AgNO₃ and 0.100 M in Pb(NO₃) ₂. A concentrated solution of Na₂CO₃ (s) is added slowly. Assuming no dilution, what is [Ag⁺] when PbCO₃ (s) starts to precipitate?
For Ag₂CO₃, K _sp = 8.2×10 ^{- 12}. For PbCO₃, K _sp = 3.3×10 ^{- 14}.

A) 0.100
B) 4.0×10 ^{- 5}
C) 8.2×10 ^{- 10}
D) 3.3×10 ^{- 13}
E) none of these