Ice will form on small ponds when the temperature drops below 0C. Which property of ice is most beneficial to fish living in these ponds?

Available options:
[A]. Ice has a temperature colder than the temperature of water.;
[B]. Ice absorbs sunlight that is reflected by water.;
[C]. Ice traps more pollution than is trapped by water.;
[D]. Ice had a density lower than the density of water.;
[D].