Which of the following is a simple sentence?
a. though some people believe a non-fatal snake bit can create immunity to snake venom, they have actually probably received only a dry bite during which the snake released little venom.
b. snakes are important, but most people don't like them.
c. pythons have become a problem in the everglades; thousands released during hurricane andrew have naturalized in the environment.
d. herpetologist dr. roan stevens specializes in the study of exotic snakes native to tropical rain forests.