Lightning bugs can blink themselves because of a chemical substance According to the passage, which of the following about lightning bugs is INCORRECT A: They use blinking signals to communicate. B: They use blinking signals to seek for food. C: They use blinking signals to attract their own species. D: They use blinking signals to frighten and warn enemies.

4. Blinking helps ________ the surface of the eye with tears, washing away dust and other irritants and keeping the sight clear.