ANS:B - straight line

If the temperature difference between the hot liquid and the room is plotted against time on a logarithmic scale, the resulting plot will very nearly be a straight line. This is because the rate of temperature change (and thus the temperature difference) between the hot liquid and the room typically decreases exponentially over time as the liquid approaches thermal equilibrium with the room. Plotting this exponential decay on a logarithmic scale often results in a straight line. Therefore, the correct answer is: straight line