Question

the surface of the road where aggregate is placed is called the _____.
o grade
o shoulder
o subgrade
o surface

Explanation:

In road - building, the subgrade is the layer of soil or rock upon which the aggregate (such as gravel, sand, etc.) is placed. The grade refers to the slope of the road, the shoulder is the part of the road adjacent to the travel lanes, and the surface is the top - most layer that vehicles drive on.

Answer:

C. subgrade