You're teaching a lesson and Stanley burps loudly. You give him the look but do not otherwise react. He does it again - this time, a really loud, long burp. You say, Stanley, you are rude to burp out loud like that. How gross. Your response is

a. effective, because it clearly states which behavior is offensive.
b. effective, because when disciplining students, the teacher should not minimize his/her own personal response.
c. ineffective, because you should always address misbehavior in private.
d. ineffective, because you have labeled Stanley in your statement.