Marketing by emailing is on the increase. Compared to other media, email messages are extremely cheap to send. With TV, you are spending on ad agencies and cable channels. With print ads, you are helping to keep newspapers and magazines alive. Direct mail costs more than $600 per thousand pieces. With email, there are almost no costs at all. Its low cost makes email marketing become the most cost-effective (划算的) advertising method available today.By saying “with print ads, you are helping to keep newspapers and magazines alive”, the writer means that _____.

A. your investment is important to newspapers and magazines
B. your ads are helping newspapers and magazines survive
C. print ads are more attractive than TV and email ads
D. print matters are less expensive than emails