C. To support the main idea.
It means like don't over use it or don't under use it. Use it for when you need it and when its important rather then use it for something that doesn't matter.
The answers from the choices above are the 2nd option and the 3rd option!
Answer:
Other nonverbal ways to display confidence include having good posture, maintaining appropriate eye contact, and smiling. Practicing ahead of time will help you appear competent, but you should listen carefully and make sure you are answering the question asked.
