@LaurenC the problem with (A) is that the principles of etiquette set forth in the stimulus do not deal with being gruff or unfriendly.
The principles set forth deal with "obscene and malicious talk" and "offensive, disturbing, or controversial ideas."
Compare (A) with (E), which deals with "name-calling" during a panel discussion about a divisive moral issue.
So this is a situation where the expression of potentially offensive, disturbing, or controversial ideas is appropriate and the principle set forth in the stimulus requires that the expression and discussion of such ideas to be done in a civil manner, i.e. no name-calling.
So (E) would most closely correspond to the principles of etiquette set forth in the stimulus.
Hope that helps! Please let us know if you have any other questions.