The correct answer is C. Facilitator.
Step-by-step explanation:
In group discussions, it is common there are different roles as this guarantees the discussion can develop properly and is effective. In the case of the facilitation, this is one of the most important roles as the facilitator is commonly in charge of leading the discussion, which means he or she introduces the topic, objectives, and rules of the discussion; also, he or she assigns turns for participants to speak and ensures everyone participates by assigning turns and time to everyone including those that might seem reluctant or shy. Thus, the role described is Facilitator.