Answer:
c. There appear to be 20% more sales of horror books than cookbooks, but there are really only about 10% more.
Explanation:
To find the answer we have to find the percentage representation of each genre. To do that, we divide the frequency by the total numbers sold:
Horror books:

Cookbooks:

So, 26% of number sold are horror books, and 16% are cookbooks. So, there are 10% horror books sold that cookbooks.
Therefore, the answer is c.