It is the measuring tool used for measuring and setting of angles

Protractors

Explanation:

A protractor is a measuring instrument, typically made of transparent plastic or metal, for measuring angles. Some protractors are simple half-discs. More advanced protractors, such as the bevel protractor, have one or two swinging arms, which can be used to help measure the angle.

A Protractor

Explanation:

The simplest protractor comprises a semicircular disk graduated in degrees—from 0° to 180°. It is an ancient device that was already in use during the 13th century.

answer; fair labor and standard act;

i would say b. research typically uses a variety of sources