Question

The three horizons in Figure 7-1 make up a soil ____________________.

Answer 1

The three horizons make up a soil profile. A soil profile is an overview that shows each of the soil's horizons. A soil horizon is each distinct layer of a soil composition. 

Answer 2

Multiple soil horizons make up a soil profile. Soil horizons are distinguishable regions of soil. They run parallel to the surface and have different characteristics. The soil horizons include the A horizon, E horizon, B horizon and C horizons.
The soil profile is a vertical cross section showing these horizons.