Detailed Explanation:

When ice floats in water, it displaces a volume of water equal to its own weight. By Archimedes' principle, the mass of displaced water equals the mass of the ice.

When the ice melts, it converts into water of exactly the same mass and occupies the same volume as the water it originally displaced. Therefore, the water level remains unchanged.

Therefore, the water level will not change, making Option 4 the correct answer.