18.

The graph represents the linear relationship between the number of books Layla has read and the number of months she has been a member of a book club.

Which of these statements is supported by the rate of change in this relationship?
Layla read 2 books in the first 3 months she was a member of the book club.
Layla read 3 books in the first 2 months she was a member of the book club.
Layla read 3 books in the first 4 months she was a member of the book club.
Layla read 4 books in the first 3 months she was a member of the book club.

The statement "Layla read 4 books in the first 3 months she was a member of the book club" is supported by the rate of change in the relationship because it indicates an increasing rate of books read per month.