Where is Newton's Law of Cooling used?

Read the following statements:

(A) When small temperature difference between a liquid and its surrounding is doubled, the rate of loss of heat of the liquid becomes twice.

(B) Two bodies P and Q having equal surface areas are maintained at temperature 10°C and 20°C. The thermal radiation emitted in a given time by P and Q are in the ratio 1:1. 15.

(C) A Carnot Engine working between 100K and 400K has an efficiency of 75%.                                    

(D) When small temperature difference between a liquid and its surrounding is quadrupled, the rate of loss of heat of the liquid becomes twice.