The reservoir for the gaseous type of bio-geo chemical cycle exists in:

Options

A. stratoshere
B. atmosphere
C. ionosphere
D. lithosphere

Explanation

### Step-by-Step Solution:

1. **Understanding Biogeochemical Cycles**:
- Biogeochemical cycles are processes that recycle nutrients in various chemical forms from the environment to organisms and then back to the environment. These cycles can be categorized into two types: gaseous and sedimentary cycles.

2. **Identifying Gaseous Cycles**:
- The gaseous biogeochemical cycles include the nitrogen cycle and the carbon cycle. In these cycles, the main reservoirs of the nutrients are found in the atmosphere.

3. **Defining Reservoirs**:
- A reservoir is a storage location for nutrients. For gaseous cycles, the reservoir is primarily the atmosphere, where gases like nitrogen and carbon dioxide are stored.

4. **Differentiating Between Types of Reservoirs**:
- There are two main types of reservoirs:
- **Gaseous Reservoirs**: Found in the atmosphere (for gaseous cycles).
- **Sedimentary Reservoirs**: Found in the earth's crust (for sedimentary cycles).

5. **Analyzing the Options**:
- The question provides several options: stratosphere, atmosphere, ionosphere, and lithosphere.
- The stratosphere, ionosphere, and lithosphere are all parts of the atmosphere and do not serve as distinct reservoirs for the gaseous cycles.

6. **Conclusion**:
- Since the atmosphere serves as the main reservoir for the gaseous type of biogeochemical cycles, the correct answer is **atmosphere**.

### Final Answer:
The reservoir for the gaseous type of biogeochemical cycle exists in the **atmosphere**.