Assertion : The melting point of ice decreases with increase of pressure
Reason : Ice contract on melting.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are truw but reason is not correct explanation of assertion
C. If assertion is true but reason is false
D. If both assertion and reason are false.

Explanation

To solve the question, we need to analyze both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "The melting point of ice decreases with an increase in pressure."
- This is based on the principle that for most substances, an increase in pressure raises the melting point. However, water is an exception due to its unique properties.

2. **Understanding the Reason**:
- The reason states that "Ice contracts on melting."
- When ice (solid water) melts, it actually occupies less volume than it did as a solid. This is a unique characteristic of water.

3. **Analyzing the Phase Change**:
- When ice melts, it transforms from a solid to a liquid. During this phase change, the volume of water decreases initially (when ice melts to form water at 0°C).
- According to the principles of thermodynamics, if the volume decreases upon melting, applying pressure will favor the formation of the liquid phase, thus lowering the melting point.

4. **Applying the Concept of Pressure and Volume**:
- According to Boyle's Law, pressure is inversely proportional to volume. If the volume decreases (as it does when ice melts), the pressure increases.
- Therefore, an increase in pressure will lead to a decrease in the melting point of ice.

5. **Conclusion**:
- Both the assertion and the reason are correct. The assertion is true because the melting point of ice does decrease with an increase in pressure, and the reason is also true because ice does contract upon melting, which explains the assertion.

### Final Answer:
- Both the assertion and the reason are correct, and the reason is the correct explanation of the assertion.