A block of mass M is released from rest at point 1, as shown in the figure. The block slides without frictional forces along the circular arc but encounters frictional forces as soon as it reaches the horizontal
portion of the track at point 2. The block travels a distance D along the horizontal track before coming to
rest at point 3. Consider the block-Earth system. In terms of the mechanical energy of the system, which of
the following claims is correct, and why?