The colloidal solution among the following is

Options

A. milk
B. oil in water
C. kerosene in water
D. chalk powder in water.

Explanation

To determine which of the given options is a colloidal solution, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding Colloidal Solutions**:
- A colloidal solution is a mixture where tiny particles of one substance are dispersed in another substance. These particles are larger than molecules but smaller than those in a suspension, and they do not settle out upon standing.

2. **Analyzing Option 1: Milk**:
- Milk is a colloidal solution where liquid fat is dispersed in water. The fat droplets are small enough to remain suspended and do not settle out, making milk a colloidal solution.
- **Conclusion**: Milk is a colloidal solution.

3. **Analyzing Option 2: Oil in Water**:
- Oil in water can form different types of mixtures depending on the amount of oil and how it is mixed.
- If a small amount of oil is mixed with a large amount of water, it can form a solution.
- If more oil is added, it can form a suspension where oil droplets do not dissolve but remain suspended.
- **Conclusion**: This option is not definitively a colloidal solution as it can vary.

4. **Analyzing Option 3: Kerosene in Water**:
- Similar to oil in water, kerosene can also form a solution, suspension, or remain as separate layers depending on the proportions.
- **Conclusion**: This option is also not definitively a colloidal solution.

5. **Analyzing Option 4: Chalk Powder in Water**:
- When chalk powder is mixed with water, it forms a suspension. The chalk particles are larger and will settle out over time, which does not qualify as a colloidal solution.
- **Conclusion**: Chalk powder in water is a suspension, not a colloidal solution.

### Final Conclusion:
- The only option that qualifies as a colloidal solution is **Option 1: Milk**.