Physics

Problem

Which of the following correctly explains why aquatic life can survive in a pond even when the surface water freezes during severe winter? a)

\text{Ice is a good conductor of heat, so heat from the deeper water flows upward through it keeping water below from freezing.}

\text{High pressure at the bottom of the pond lowers the freezing point of water, so the deep water stays liquid.}

\text{Water at }4^{\circ}\text{C}\text{, being densest, settles at the bottom, so liquid water remains beneath the ice layer.}

\text{Water colder than }0^{\circ}\text{C}\text{ sinks, keeping the lower layers liquid.}