The Initial and Very Rapid Recession of the Edge of the White

Multiple Choice

The initial and very rapid recession of the edge of the white polar cap region toward the poles in springtime is caused by:

A) the melting and evaporation of CO₂ ice.
B) the increased growth of vegetation toward the poles from mid latitudes.
C) the change in color of the rocks by photochemical action, similar to bleaching.
D) the melting of H₂O ice and subsequent runoff of water.