Read the excerpt from "are dogs dumb? ":

chimps can use sign language to talk to their trainers. monkeys can learn to count. a crow can figure out how to use a stick to get at that hard-to-reach grub. chickens can learn to play checkers. even worms can be taught to run mazes. so which animal is the smartest? you're probably thinking that chimps are smarter than chickens. and that crows are smarter than worms. and that you’re smarter than all of them.

which statement best explains how the passage supports the author's purpose?

the purpose is to entertain; it uses a humourous tone.

the purpose is to persuade; it is trying to convince you that humans are the smartest animal of all.

the purpose is to inform; it asks a question that will be answered by the text.

the purpose is to instruct; it provides many supporting details about the abilities of chimps.