Answer: The pair of sentences that shows the main character dealing with an internal conflict are "I was about to protest—I had never heard of a Chesterfield, for crying out loud. But I stopped. Be patient with her, my mother had said. Humor her. Be gentle."
Explanation: Just to elaborate a liitle on the answer, it can be added that the last excerpt can be discarded, since it does not show an internal conflict. It is just describing the way one of the characters behaved. Likewise, the second excerpt shows that the main character does not like to be called "dear" by the attendant, and he does not reveal his displeasure, but that cannot be described as an internal conflict. The first excerpt, however, does show that the said character is dealing with an internal conflict: his urge to protest and reveal his anger, and his decision to be patient and refrain from doing so.