What Is the First Question in the Three Main Steps

What is the first question in the three main steps in Fourth Amendment analyses?

A) Was the law enforcement action a "search" or a "seizure"?
B) If the action was a search or a seizure, was it reasonable?
C) If the action was an unreasonable search, does the Fourth Amendment ban its use as evidence?
D) If the action was reasonable, can the evidence be used to impeach a witness?