Mineral functioning as chemical messenger is

Options

A. Calcium
B. Magnesium
C. Manganese
D. Molybdenum.

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for a mineral that functions as a chemical messenger. Chemical messengers are substances that help transmit signals within and between cells.

2. **Identifying the Options**: The options provided are:
- Calcium
- Magnesium
- Manganese
- Molybdenum

3. **Analyzing Each Option**:
- **Calcium**: Calcium ions (Ca²+) play a crucial role in cellular signaling. They act as secondary messengers in various signaling pathways, particularly in plants. Calcium is involved in transmitting signals from the outside to the inside of the cell, making it a key player in many physiological processes.
- **Magnesium**: While magnesium is essential for many enzymatic reactions and functions in cells, it does not primarily act as a chemical messenger.
- **Manganese**: Manganese is important for various metabolic processes, but it does not function as a chemical messenger.
- **Molybdenum**: Molybdenum is involved in certain enzymatic functions but is not recognized as a chemical messenger.

4. **Conclusion**: Based on the analysis, the mineral that functions as a chemical messenger is **Calcium**.

### Final Answer:
The mineral functioning as a chemical messenger is **Calcium**.

---