We have taken a saturated solution of $AgBr$. $K _{ sp }$ of $AgBr$ is $12 \times 10^{-14}$. If $10^{-7}$ mole of $AgNO _{3}$ are added to 1 litre of this solution then the conductivity of this solution in terms of $10^{-7} Sm ^{-1}$ units will be
[Given$ \lambda_{\left( Ag ^{+}\right)}^{0}=4 \times 10^{-3} Sm ^{2} mol ^{-1}\lambda_{\left( Br ^{-}\right)}^{0}=6 \times 10^{-3} S m ^{2} mol ^{-1}, \lambda_{\left( NO _{3}^{-}\right)}^{0}=5 \times 10^{-3} Sm ^{2} mol ^{-1}$ ]
(A) 39
(B) 55
(C) 15
(D) 41