For the reaction C2H6(g)+nO2⟶CO2(g)+H2O(l), the ratio of the coefficients of CO2 and H2O is:
1:1
2:3
3:2
1:3
The balanced equation is: 2C2H6+7O2⟶4CO2+6H2O. As you can see - the ratio of the coefficients of CO2 and H2O is 4:6 or 2:3.