Bone is the homeostatic reservoir of  

Options

A. (NPK) sodium, phosphoran & potassium
B. calcium, soidum, phosphorous
C. calcium, magnesium & zinc
D. calcium, magnesium & phosphorous

Answer

To solve the question "Bone is the homeostatic reservoir of," we will analyze the options provided and determine which elements are primarily stored in the bones.

### Step-by-Step Solution:

1. **Understanding the Role of Bones**:
- Bones serve as a reservoir for various minerals in the body. They play a crucial role in maintaining homeostasis, particularly in regulating mineral levels in the blood.

2. **Identifying Key Minerals in Bones**:
- The most significant minerals stored in bones are calcium and phosphorus. Bones contain about 99% of the body's calcium and a significant amount of phosphorus (approximately 80-90% of the body's phosphorus).

3. **Evaluating the Options**:
- **Option 1: NPK (Sodium, Phosphorus, and Potassium)**:
- While phosphorus is indeed stored in bones, calcium is missing from this option, making it incorrect.
- **Option 2: Calcium**:
- Calcium is a crucial mineral stored in bones, but this option does not mention other minerals, making it incomplete.
- **Option 3: Sodium and Phosphorus**:
- Sodium is present in bones, but this option lacks calcium, which is essential for bone function.
- **Option 4: Calcium, Sodium, and Phosphorus**:
- This option includes calcium, which is the primary mineral in bones, along with sodium and phosphorus, making it the most comprehensive and correct choice.

4. **Conclusion**:
- Based on the analysis, the correct answer is **Calcium, Sodium, and Phosphorus**. Bones serve as a homeostatic reservoir for these minerals.

### Final Answer:
Bone is the homeostatic reservoir of **Calcium, Sodium, and Phosphorus**.