It is by listening and evaluating the speaker's questions and responses. When the speaker asks a question, he is surely making a point to the audience through his responses. By that kind of communication, the speaker should have given his purpose to the audiences.
What is Stevie’s last name?
Answer:
C. To find out if the call of an animal is missing
Explanation:
The more scientists listen to these kinds of recordings, the more they notice when an expected call is missing.
I hope this helps you in any shape or form.
C.) p<span>olio is a contagious *disease* that has mostly been eradicated.</span>
Your tone
Let's look at the other choices first. Your credibility is your ability to be believed as trustworthy in regards to the subject. Whether you're talking to a group of teenagers or professional adults, your credibility doesn't change. Your clarity also should not change based on the audience because you want to be clear in your message at all times. Also, your purpose should be the same no matter the audience. The only thing that would change is your tone. The way you approach a crowd of teenagers would vary greatly from the way you'd approach a room of professionals.