Final answer:
Frozen water floats on liquid water, providing an insulating barrier for fish in a lake.(Option D)
Step-by-step explanation:
The characteristic of water that is most helpful to fish in a lake is that frozen water floats on liquid water.
When water freezes, it becomes less dense and expands. This causes it to float on the surface of the lake instead of sinking to the bottom. The layer of ice acts as an insulating barrier, providing protection for the fish living in the liquid water beneath.
Without this characteristic, the lake would freeze solid from the bottom up, making it impossible for fish and other organisms to survive.This unique property of water, where frozen water floats, not only forms an insulating barrier crucial for fish survival but also prevents lakes from freezing solid, ensuring the viability of ecosystems and the diverse organisms that rely on liquid water habitats.