We are told that some vegetarians argue two individually sufficient reasons for not eating meat: (1) health concerns and (2) creatures have consciousness. The argument asks us to suppose that eating meat was actually good for one's health. It states that if this were true, then it is LESS CLEAR that an aversion to living at the expense of other conscious creatures is a sufficient reason to stop eating meat.
Answer choice (E) states: "it is used to show that there is no sufficient reason for not eating meat."
Well, this is much too strong. The argument isn't using the supposition to show that there are NO sufficient reasons for not eating meat, it uses it, rather to show that if the supposition were true, then it is LESS CLEAR (as opposed to completely clear) whether the consciousness of creatures is a sufficient reason to stop eating meat. So, the supposition is merely being used to weaken the claim that concern for conscious creatures will be a sufficient reason not to eat meat.
Hope that helps! Please let us know if you have any other questions.
