Why Do Ice Cubes Get Smaller When Left in the Freezer

Why do ice cubes get smaller when left in the freezer for a long time?

A) The ice cubes melt during the brief warming cycles of auto-defrost and freezer access, thus leaving the ice cubes smaller and making them stick together in clumps.
B) The water molecules of the ice sublime from the solid to gaseous phase without ever entering a liquid phase.
C) Both A and B occur.
D) Neither A nor B accurately explain why ice cubes get smaller in the freezer over time.