The first step in the construction of a perpendicular bisector is represented by the second response:
"A line segment has 2 end points. The left end point is A, and the right is B. A geometric compass is shown with the compass needle on point A and the pencil of the compass placed about two thirds of the way along line segment A B."
This step involves placing the compass on one endpoint and drawing an arc that will eventually help locate the points necessary for creating the perpendicular bisector.