Two mixtures A and B have the following compositions:
Mixture A has copper and tin in a ratio of 1:2
Mixture B has copper and tin in a ratio of 1:3
If equal quantities of mixtures A and B are used for producing mixture C, then find the ratio of copper and tin in mixture C.

A

2 : 5

B

l : 5

C

7 : 1 7

D

7 : 12