Answer:
Among the options given on the question the correct answer is option B.\
Foot-in-the-door.
Explanation: The persuasion techniques are the ways to influence something or somebody in order to pursue something. There are many persuasion technique which are used to pursue anything.
The foot in the door is persuasion technique is process which principal is before asking any big favor or change it is necessary to ask for small change and favor.This persuasion technique is used before changing something big. It is easy to change something smaller at first. Because it will make the subjected people ready to accept for a bigger change.
Therefore, the answer of the question is foot-in-the-door.