Which one of the following has septate and branched mycelium and involved decomposition of litter and helps in mineral cycling.

Options

A. Alternaria
B. Colletotrichum
C. Trichoderma
D. All of the above

Answer

To solve the question regarding which organism has septate and branched mycelium, is involved in the decomposition of litter, and helps in mineral cycling, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Characteristics**:
- We need to identify the characteristics mentioned in the question: septate and branched mycelium, involvement in decomposition, and contribution to mineral cycling.

2. **Identifying the Options**:
- The options provided are:
1. Alternaria
2. Colletotrichum
3. Trichoderma
4. All of the above

3. **Analyzing Each Option**:
- **Alternaria**: This is a genus of fungi known to have septate mycelium and is involved in the decomposition of organic matter.
- **Colletotrichum**: This genus also has septate mycelium and is known for its role in decomposing plant material.
- **Trichoderma**: This genus is well-known for its decomposing abilities and has septate, branched mycelium.

4. **Conclusion**:
- All three options (Alternaria, Colletotrichum, and Trichoderma) share the characteristics of having septate and branched mycelium and are involved in the decomposition of litter and mineral cycling. Therefore, the correct answer is **D. All of the above**.

### Final Answer:
**D. All of the above**