Which of the Following Is Not an Example of Noise

Which of the following is not an example of noise in the communication process in a typical classroom?

A) A student in the back of the classroom texting a friend.
B) Groundskeepers mowing the lawn outside the classroom window.
C) A student responding to a professor's request for questions.
D) Uncomfortable classroom desks.
E) An attractive person walking by the open classroom door.