Although you may never see one of these night flyers, bats comprise close to a quarter of the world’s entire mammal population. What are many of these bats doing as they dart about in the wee hours? They are eating insects. One Big Brown bat, for example, can easily eat 5,000 mosquitoes a night. What an efficient—and safe—insect eradicator! Bats also spend time pollinating food plants, spreading seeds, and controlling crop parasites. Which sentence best expresses the main idea of the selection? Immersive Reader

Bats are small but amazing creatures.
Bats play an important role in a healthful environment.
Bats eat insects, pollinate plants, spread seeds, and control parasites.
Bats are the only mammals that fly.