In the Context of Paper Presentations, Which of the Following

In the context of paper presentations, which of the following statements is true about oral presentations?

A) Authors can speak extensively with other people who are doing research in their area.
B) Authors are advised to give a detailed summary of their earlier researches.
C) Authors usually prefer describing methods and complex results, rather than relying on visual aids.
D) Authors are usually given a limited time to present their information.