The correct answer would be C, To help speakers stay on topic.
Explanation:
When a formal discussion is held, there are many experts who have their own set of ideas and who have vast knowledge in their respective fields. So if they are asked to take part in the discussion, they can move the discussion to some other direction. So to avoid such problems, it is necessary to make rules and guideline before starting a formal discussion so that the speakers stay on the topic and don't move towards the other topics. In this way the time will be managed efficiently and people can get the best out of the useful discussion on the proposed topic.
