Answer: The correct answer for the fill in the blank is C) Use body language to understand how a speaker feels.
Active listening is a particular skill that a person can acquire through constant practice. A person uses all of his/her senses in active listening. The person responds to the speaker through verbal and non verbal means ( like nodding, maintaining eye contact) that encourages the speaker to continue with their speech.
Providing positive feedback in the form of body language makes the speaker feel more comfortable so that he speak more comfortably and frankly.
Thus, option C) is the right answer.