The process through which fungi break down dead organic matter is known as what?

The correct answer is decomposition. This process involves the breakdown of dead organic material by fungi, bacteria, and other decomposers, allowing nutrients to be recycled back into the ecosystem. Decomposition is a crucial part of the nutrient cycle, contributing to soil fertility and promoting plant growth.

Fungi are particularly effective decomposers due to their ability to produce enzymes that can break down complex organic substances such as cellulose and lignin found in plant material. This breakdown not only helps to return nutrients to the soil but also can support the formation of humus, which improves soil structure and water retention.

Other processes listed have distinct purposes: photosynthesis is the process by which plants convert light energy into chemical energy, composting refers to the managed decomposition of organic matter to create nutrient-rich soil amendments, and fermentation is an anaerobic process that converts sugars into alcohol or acids. Each of these plays vital roles in their environments but does not specifically describe the general breakdown of dead organic matter as effectively as decomposition does.