Answer:
(A) Knowing the subject.
Explanation:
For any type of speaking, be it publicly or just a simple speech for a group, the most important and first priority should be the familiarity of the topic by the author.
An orator or speaker may have a good speaking voice, have great body language, great presentation skills, stage performance and even uses figurative languages. But all these can amount to nothing if the topic is not fully grasped and understood by him. The most important character of the speech will depend on the knowledge of the speaker about the topic.
