The following bar graph shows the sales (in thousands) of books from six different branches of a publishing company in 2000 and 2001.

Answer the following question based on the bar graph:
What is the ratio of the total sales of C3 for both years to the total sales of C4 for both years?

A

14 : 15

B

15 : 14

C

13 : 14

D

12 : 13