What is the first step in the construction of a line perpendicular to ab←→ and passing through an external point m? assume that the construction uses only a compass and a straightedge.

a.) place the compass needle on m and, keeping the compass width the same, draw two arcs that intersect ab←→.
b.) place the compass needle at any point on ab←→, and set the compass width to m.
c.) draw a line from point m passing through ab←→, and mark the point of intersection.
d.) place the compass needle at any two points on ab←→, and draw two arcs through m.