Biogeochemical cycles are of

Options

A. Two types
B. Three types
C. Four types
D. Five types

Explanation

### Step-by-Step Solution:

1. **Understanding Biogeochemical Cycles**:
- Biogeochemical cycles refer to the cycles that involve the movement of elements and compounds through biological (living organisms), geological (earth), and chemical (atmosphere) processes.

2. **Identifying the Types of Biogeochemical Cycles**:
- Biogeochemical cycles can be classified into two main types:
- **Gaseous Cycles**: These cycles involve elements that exist in the atmosphere and can be found in gaseous form. Examples include the oxygen cycle and the nitrogen cycle.
- **Sedimentary Cycles**: These cycles involve elements that are primarily found in the earth's crust and are not gaseous. An example of this is the phosphorus cycle.

3. **Conclusion**:
- Based on the classification, biogeochemical cycles are of two types: gaseous cycles and sedimentary cycles.

4. **Final Answer**:
- Therefore, the correct answer to the question is that biogeochemical cycles are of **two types**.