Here's a problem to solve: Which property of water is essential for organisms to survive in freshwater ponds during the winter months?

Among the 4 following options, which is the correct answer?

- A: Water is a polar molecule.
 
- B: Water has a high surface tension.
 
- C: Water can change from a solid directly to a gas.
 
- D: Water is less dense as a solid than as a liquid.
 