Read this sentence from neil degrasse tyson's preface to his book the pluto files:

the pluto files chronicles and documents pluto's remarkable grip on the hearts and minds of the american public, the professionals, and the press.
why would this be considered an example of expository writing?

a. it reviews tyson's book and offers an opinion.
b. it informs the reader about the public's love of pluto.
c. it argues that people should not care so much about pluto.
d. it provides a fictionalized account of pluto's history.