The graph below shows the changes in the temperature of ice when it is heated from -20 °C to 100 °C. Heat curve for ice. The graph shows the changes in the temperature of ice when it is heated from negative 20 degrees Celsius to 100 degrees Celsius. The label for the x-axis reads 'Addition of heat over time.' The label for the y-axis reads 'Temperature (degrees Celsius).' There are labels on the graph (from 'A' to 'E') that designate significant events while applying heat to the ice. Portion AB has a slight incline while increasing the heat from negative 20 degrees to 5 degrees; portion BC stays at 5 degrees for a while; portion CD steadily increases in temperature from 5 degrees to 100 degrees over a significant period of time; portion DE stays at 100 degrees for a while.

Based on the graph, which of these conclusions is correct?