Which horizon represents the parent material in soil profiles?

The C horizon is indeed the correct choice as it represents the parent material in soil profiles. This layer consists primarily of weathered rock and unconsolidated material from which the soil develops. It serves as the foundational layer beneath the soil’s upper horizons, such as the A and B horizons, and contains the minerals and organic materials that are gradually broken down and transformed into soil through various processes, including weathering and biotic activity.

In contrast, the A horizon, known as the topsoil, is rich in organic material and nutrients, supporting plant growth. The B horizon, or subsoil, accumulates minerals and organic matter leached from the upper layers, but it is not considered the parent material itself. The O horizon consists mainly of organic matter, like decomposed leaves and plant material, found at the surface in forested and grassland areas. Each of these horizons plays a unique role in soil composition and fertility, but only the C horizon directly represents the underlying parent material.