Purchases OHaganBooks.com has been promoting a number of books published a...

Purchases OHaganBooks.com has been promoting a number of books published at Duffin House. The following table shows the number of books purchased each month from Duffin House for the past five months:

a. Which of the following models best approximates the data?

b. What do each of the above models predict for the number of new users in the next few months: rising, falling, leveling off, or something else?