Question

when constructing a congruent angle, measure the length of the arc drawn with a
rular
protractor
compass
straightedge

Explanation:

A compass is used to draw arcs of a certain radius when constructing congruent angles. A protractor measures angles, a straight - edge helps in drawing straight lines and a ruler measures lengths of straight - line segments, not arc lengths in the context of angle construction.

Answer:

C. compass