If you want your listeners to believe your ideas what must you establish?

In the introduction of his persuasive speech on the advantages of geothermal energy,

Jose says, "Geothermal energy can supply much of the United States` electric needs at competitive prices". What function does this part of Jose's introduction serve? A) Establishing his credibility B) Clarifying his purpose by advancing his thesis C) Grabbing the audience's attention D) Previewing his main points

Explain the steps you should take to prepare for a question-and-answer session.

What will be an ideal response?