Final answer:
Sonia uses the door-in-the-face technique by first asking for more money than needed and then reducing the request to the actual amount required, making it seem more reasonable to her brother.
Step-by-step explanation:
The compliance technique Sonia is using is a) Door-in-the-face technique. This is a method where someone makes a large, unreasonable request that is expected to be refused, and then follows it with a much more reasonable, smaller request. Sonia initially asks her brother for $100 for a textbook, anticipating refusal, and then suggests the actual amount she needs, $75, which now seems more reasonable by comparison.
The foot-in-the-door technique is a different compliance strategy that involves gaining a person's agreement to a small request as a precursor to a larger request. It is based on the principle of consistency; once we have agreed to a small request, we are more likely to agree to a larger one in order to maintain internal consistency. An everyday example of this might be a teen asking their parents for a minor favor before asking for something considerably larger.