An architect plans to make a drawing of the room of a house. The segment LM represents the ceiling of the room. He wants to construct a line passing through Q and perpendicular to side LM to represent a wall of the room. He uses a straightedge and compass to complete some steps of the construction, as shown below:

A line segment LM is drawn. A point Q is below L. A small arc intersects LM on the left of L at P. A compass is fixed at Q and is shown making an arc at P.

Which of these is likely to be his next step in constructing the perpendicular line?

A. Fix the compass at Q, and draw an arc below the line.
B. Fix the compass at L, and draw an arc above the line.
C. Without changing the width and position of the compass, draw an arc between L and M.
D. Without changing the width of the compass, place the compass at M and draw an arc.