Public speaking skills takes the speaker's connection with his audience as the most important point. The first requirement is that, you should know what you;re talking about. Your visual presentation or piece should only guide you but you can't totally depend on it. The speaker has to know his audience and engage them into thinking and conversing. Public speaking is also like a trial-and-error process. You don't get it right the first time, it takes practice. Thus, the answer is letter D.
