Although the Polar Regions Radiate Away More Heat Energy Than

Although the polar regions radiate away more heat energy than they receive by insolation in the course of a year, they are prevented from becoming progressively colder each year by the ____.

A) conduction of heat through the interior of Earth
B) concentration of Earth's magnetic field lines at the poles
C) circulation of heat by the atmosphere and oceans
D) the insulating properties of snow
E) release of latent heat to the atmosphere when polar ice melts