If 49 litres of a milk solution has 63% milk in it, then how much milk should be added to make the concentration of milk 70% in the solution?

A

$$11\frac{13}{30}$$ litres

B

$$14\frac{7}{30}$$ litres

C

$$12\frac{11}{30}$$ litres

D

$$13\frac{1}{30}$$ litres