Answer: The answer is option B, response cost. Response cost is the removal of reinforcement for a particular undesired behavior or habit. It is sometimes identified as a firm if negative punishment.
Explanation: The undesirable behavior here is Dawn's habit of screaming to her Mom. And having had enough of it, her mom decides to nip the situation in the bud by not answering (which is the response cost) so that Dawn would seize to continue with the habit.
This is true and quite probably the best explanations of how relative pronouns and antecedents work in a language.
I believe it is A. Because of the last sentence saying there would be no indication that it was us who put it their.