A boat is containing leaves. When they are throw into the water, the level of water in the lake

• When leaves are tossed into water, they now float on their own, displace water equal to their individual weights, unlike when the boat containing the leaves was floating in the water, which would have displaced water equal to (Boat + leaves) weight. 
• The total volume of water displaced by the combined weight of the boat and leaves is equal to the volume of water displaced by the boat and leaves separately, according to our calculations. As a result, the lake's water level is unaltered.

Hence the correct answer is remains same.