Which statement accurately compares archaebacteria and eubacteria? Both take different shapes and sizes.
Both are always heterotrophs.
Both can sometimes live in extreme environments.
Both are known as "true" bacteria.

According to the article, what valid claim came from the national research council? there is no association between fluoride exposure and increased cancer risk in humans. there is a possible link between fluoride exposure and increased cancer risk in humans. there is a definite link between fluoride exposure and increased cancer risk in humans.