The ratio of copper and zinc in alloy A is 5:7 and that in alloy B is 4:5. A and B are taken in the ratio of 1:2 and mixed to form a new alloy C. What pa11 of C is copper?

A

$$\frac{47}{108}$$

B

$$\frac{5}{12}$$

C

$$\frac{4}{9}$$

D

$$\frac{61}{108}$$