Which of the following is NOT a component of soil?

Soil is typically composed of four main components: mineral matter, organic matter, water (moisture), and air. Each of these components plays a critical role in the formation and functionality of soil. Mineral matter consists of the inorganic particles that provide structure and nutrient supply. Organic matter, derived from decaying plant and animal material, contributes to the soil's fertility and supports biological activity. Moisture is essential for chemical and biological processes within the soil, while air fills the spaces between soil particles, allowing for gas exchange.

Heat, while it can influence soil processes and promote biological activity, is not considered a physical component of soil itself. Instead, it is an environmental factor affecting soil behaviors, such as temperature and moisture retention. Therefore, the correct answer identifies heat as not being a component of soil, highlighting the distinctive classification of soil's physical makeup and the processes that operate within it.