The graph shows the changes in the phase of ice when it is heated. A graph is plotted with temperature in degree Celsius on the y axis and Time in minutes on the x axis. The temperature at time 0 minute is labeled A, the temperature at time 2 minutes is labeled B, the temperature at time 25 minutes is labeled C, the temperature at time 80 is labeled D. Graph consists of five parts consisting of straight lines. The first straight line joins points 0, A and 2, B. The second straight line is a horizontal line joining 2, B and 12, B. Third straight line joins 12, B and 25, C. Fourth straight line is a horizontal line which joins 25, C and 80, C. Fifth straight line joins 78, C and 80, D.

Which of the following temperatures describes the value of A? (4 points)

a
0 °C, because it is the melting point of ice.

b
0 °C, because it is the freezing point of water.

c
Less than 0 °C, because B represents the temperature at which ice melts.

d
Less than 0 °C, because B represents the temperature at which water evaporates.