Which logical fallacy is used in the text?
My opponent claims that testing products on animals is cruel. But I, for one, cannot support exposing humans to harmful chemicals!

 - circular reasoning: an argument that supports a claim with the claim itself
 - straw man: a misrepresentation of an opponent's position that makes it easier to argue against
 - slippery slope fallacy: the false assumption that a small first step will lead to extreme consequences
The text argues that the speaker's opponent supports exposing humans to harmful chemicals. However, the speaker's opponent only argued against testing products on animals. This illustrates a type of logical fallacy known as a straw man.