3. a line perpendicular to a given line through a point not on the line
Step-by-step explanation:
The point not on the line suggests that choices 1 and 3 are possibilities. The fact that the dotted line is not parallel (and is perpendicular) to the solid line suggests that choice 3 is applicable and choice 1 is not.
The short arcs are equidistant from the end points of the chord that intercepts the larger arc. Hence the line through the crossing point of the short arcs and the point on the other side of the line will be the perpendicular bisector of the chord, and will be perpendicular to the solid line. Creating that perpendicular is likely the purpose of the construction.
