Answer: Know what you are talking about, know when it is the right time for you to talk, have materials/ notes on hand, be confident (but not overly confident), and stay calm
Explanation: Cause in you're question it say "would probably NOT be used as support for a proposition to keep a city's public libraries open seven day's a week" and c is saying fewer and fewer are using the libraries which means c would not be used as support for a proposition.