If public funds, then...
Less time fund-raising, more time to serve the public
+
Reduce likelihood that one only works for large contributors
-->
Campaigns should be subsidized with public funds
(A) Looks good. If public funds could provide a benefit --> such funds should be provided. We know the sufficient condition is satisfied. Thus, the conclusion is reached.
(B) Terms of office lengthened? Totally irrelevant. Eliminate.
(C) Candidate's rivals? Also, do we know anything about how large contributions flow to one candidate over the other? Eliminate.
(D) This starts off well but we don't know if public funding would "inevitably produce a special benefit for special individuals." Thus, the sufficient condition has not necessarily been satisfied. Eliminate.
(E) We have no idea why these people run for office. Eliminate.