You Notice That Your Psychology Professor Has Been Varying the Intonation

Multiple Choice

You notice that your psychology professor has been varying the intonation and loudness of her voice during her lecture. What could be one explanation for this behavior?

A) She is trying to scare you into learning the material.
B) She may be ill and has a hard time controlling her voice.
C) She is trying to keep your attention to the lecture.
D) There is no reasonable explanation for this odd behavior.