lets assume that $A,B$ incomes are $4x,7x$ and their expenditures are in the ratio of $6x,11x$
Note: saving =total income-expenditure
now according to the given information:
$4x-6y=\frac{4x}{3}$
$\implies 4x=9y \implies x=\frac{9y}{4}$
so required saving ratio=$\frac{4x-6y}{7x-11y}$
put x value in given ration we get:
$\implies \frac{\frac{36y}{4}-6y}{\frac{63y}{4}-11y}$
$\implies \frac{3y}{19y/4}=\frac{12}{19}=12:19$
Option (A) is correct.