I think the OA should be (E).
The analysis of the correct answer in this case requires us to use some sample data.
e.g. If advertizers say that most orders(lets say 100) were placed by people under the age group of 30-35. Then if 30% of the orders were picked up by the subscribers (under the age of 30-35), rest should be picked up by the non subscribers (under the age of 30-35).
Hence E looks to be correct to complete the equation.
Regards
Nitin