Three-dimensional drawing in which all the sides are measured full size and scaled
with the drawing at 30° to the horizontal is known as
a. two point perspective
c. linear perspective
b. isometric perspective
d. multiple point perspective

b. isometric perspective

Explanation:

    The isometric perspective occurs when the viewer is located at infinity (and therefore the straight lines you project are parallel to each other) and fall perpendicular to the Frame Plane.

    The system of axes of the situation to be projected will occur in perspective, when viewed in the plane, equi-angularly (at 120º angles).

   In this way, an isometric perspective can be traced through an edge of lines drawn from 30 ° angles.

i believe their role is to instruct certain sections on when they are to join and when they are to stop