$A$ heater supplying constant power $P$ watts is switched $ON$ at time $t=0$ to raise the temperature of a liquid kept in a calorimeter of negligible heat capacity. $A$ student records the temperature of the liquid $T(t)$ at equal time intervals. $A$ graph is plotted with $T(t)$ on the $Y$-axis versus $t$ on the $X$-axis. Assume that there is no heat loss to the surroundings during heating. Then,

• A
  the graph is a straight line parallel to the time axis
• B
  the heat capacity of the liquid is inversely proportional to the slope of the graph
• C
  if some heat were lost at a constant rate to the surroundings during heating,the graph would be a straight line but with a larger slope
• D
  the internal energy of the liquid increases quadratically with time