Polar bears use floating pieces of sea ice as feeding platforms when hunting seals. What property of water makes this possible?

Answer is: B. Solid water is less dense than liquid water.

Solid water (ice) is less dense than liquid water because of ice's structure has a lot of space between water molecules. Water form a crystalline structure with hydrogen bonds. Solid water has more hydrogen bonds, so molecules of water are push farther apart, so ice has lower density.