The correct answer is A. Informal negative sanctions
Explanation:
In society, a sanction refers to a "punishment" or "reward" in response to the action of an individual or group that can break or preserve the social order. In this way, a sanction is positive when it ratifies or approve an action or behavior and negative when it rejects a behavior or actions. Besides this, a sanction is formal when the sanction is based on law or official institutions and informal are those based on reprimands, shaming, ridicule, etc. that show a behavior o action is negative but does not have a consequence in terms of law or institution. Considering this, in the case presented the professor uses informal negative sanction because the student is being "punished" for using her cell phone in class which is a negative sanction but this sanction is informal as it is based on ridicule and verbal reprimand but does not have a consequence in terms of law or rules such as expelling the student.