Wendell wants people to donate $100 to a cause that's important to him. He could ask them to make a donation, but first, he asks them to sign a simple petition related to the cause. He follows up this request by asking for the donation. What technique is he using to increase the chances that people will donate the large amount of money he wants?

A. Foot-in-the-door phenomenon
B. Fundamental attribution error
C. Familiarity effect
D. Cognitive dissonance