How do you know the writer used a point-by-point comparison strategy in the passage?

Select one:
a. The writer covers all the information about e-books and then print books.
b. The writer combines information about both kinds of books in each paragraph.
c. The writer moves between the two kinds of books, back and forth, throughout the passage.
d. The writer discusses e-books for several paragraphs and then discusses print books until the end.