The correct response that shows the first step in the construction of a perpendicular bisector is:
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.
In the construction of a perpendicular bisector, the first step involves placing the compass point on one endpoint (in this case, point A) and drawing an arc that extends beyond the midpoint of the line segment AB.