Answer:
The answer is B.
Step-by-step explanation:
This technique, abbreviated as FITD, states that people tend to agree to a large request if they've already complied to a smaller one. This occurs because the person might feel obliged to continue agreeing with any future requests, in an attempt to be consistent to their previous agreements.
The name of the phenomenon is an analogy to a salesperson who keeps their foot on the door, so the customer feels obliged to listen. Interestingly enough, this technique is much used in marketing.