What Does the Door-In-The-Face Technique Involve

What does the door-in-the-face technique involve

A)  Making a long series of very small requests, until the target stops agreeing. 
B)  Concealing some of the costs associated with a request until after the request has been accepted. 
C)  Making a very large request that is likely to be turned down to increase the chances that people will agree to a smaller request later. 
D)  Adding incentives to a request that has been turned down until people finally agree to go along with the initial request.