The figure below shows a circle with segment AB as it's diameter. The center of the circle is NOT known. A square needs to be inscribed in the circle with A and B as a pair of opposite vertices. Which step will be used in the construction? PLEASE HELP

A. constructing four arcs on the circles circumference with the compass width as the radius
B. constructing a segment that is tangent to the circle at point A
C. constructing a perpendicular to a line segment through a point not lying on it.
D. constructing a perpendicular bisector of a line segment.​