The correct option is Humus.
Explanation
Decomposition is the process by which decomposers break down complex organic matter into inorganic substances like carbon dioxide, water, and nutrients. The process is largely oxygen-requiring and involves important steps such as fragmentation, leaching, catabolism, humification, and mineralization.
Detailed Analysis
- Humus (Correct): Humification leads to the accumulation of a dark-coloured, amorphous substance called humus. It is highly resistant to microbial action and undergoes decomposition at an extremely slow rate. Being colloidal in nature, it serves as a reservoir of nutrients.
- Peat: Peat is an accumulation of partially decayed vegetation or organic matter that forms in unique environments (like bogs) under anaerobic conditions. It is not the general product of the standard decomposition process described in the context of humification.
- Mucus: This is a biological secretion produced by various organisms for lubrication and protection, not a product of decomposition.
- Lignin: Lignin is a complex organic polymer found in the cell walls of plants. While it is a component of the detritus that is resistant to decomposition, it is the substrate being broken down, not the amorphous substance formed during the process.
Key Takeaway
Humus is the dark, amorphous, and microbial-resistant product of humification that acts as a nutrient reservoir in the soil ecosystem.