The conclusion of the argument is that adolescents should have the right to vote.
Why? We are told that adults have the right to vote and that since adults and adolescents are not the same, adults cannot be expected to represent the interests of adolescents; so then, only by giving adolescents the right to vote will these interests be represented. Thus--our conclusion--adolescents should also have the right to vote.
As you can see, the fact that adolescents and adults are not the same is not the conclusion, but a fact that helps support the conclusion. Remember, the conclusion will never support any other part of the argument.
Therefore, answer choice (E) correctly explains what the statement pointed out in the question stem does: "It concedes a point that is then used to support the conclusion."
Hope that clears things up! Please let us know if you have any other questions.
