A

Step 1: Understand the principles of buoyancy and displacement. When ice is floating in water, it displaces an amount of water equal to its weight.
Step 2: As ice melts, it turns into water, the volume of which is exactly equal to the volume of water displaced by the ice. Therefore, the level of water in the vessel will not change when the ice melts.
Step 3: Now consider the scenario with lead inside the ice. Lead is denser than water, meaning it will contribute to the weight of the floating ice but will not change the overall displacement once melted. The level of the water remains the same.
Step 4: If there are air bubbles inside the ice, the situation changes slightly. The air bubbles will not contribute to the weight significantly, so when the ice melts, the volume of water produced will be less than the volume of water that would have been displaced by the ice. Therefore, when the ice with air bubbles melts, the water level will decrease.
Conclusion: The water level will not change when the ice with lead melts (it stays the same), while it will decrease if the ice contains air bubbles.