In a working refrigerator, the value of COP is always

Answer: Option D

We know COP of a refrigerator
$$\begin{array}{rl}& =\frac{\text{Cooling effect}}{\text{Work taken}}\\ & =\frac{Q_L}{W_{net}}\\ & =\frac{Q_2}{Q_1-Q_2}\end{array}$$
For a reversible refrigerator COP $$=\frac{T_2}{T_1-T_2}$$
Since $$T_1-T_2<T_2$$
So COP is always greater than zero.