Scientists previously thought that all electric eels belong to a single species, but a team of researchers led by zoologist C.
David de Santana proved this idea wrong by ______ that there are in fact three distinct species of electric eels.
pretending
complaining
requiring
demonstrating
Choice D is the best answer. “Demonstrating” means “showing,” and the text describes how de Santana disproved a previous
belief in only one species of electric eel by showing that three electric eel species actually exist.
Choice A is incorrect. Pretending that there are three species of electric eel might be a fun game for marine biologists, but it
wouldn’t prove the existence of more than one species. Choice B is incorrect. Complaining won’t prove anything about eels,
so de Santana could not have proved wrong the idea of only one species of electric eel by complaining about it. Choice C is
incorrect. “Requiring” means “needing.” It wouldn’t make sense to say that de Santana “needed” there to be three distinct
species of electric eel.