A System under goes a Cyclic Process in which it absorbs $\mathrm{Q}_{1}$ heat and gives out $\mathrm{Q}_{2}$ heat. The efficiency of the Process
$\eta$ and the work done is $\mathrm{W}$. Which formula is wrong ? is
(A) $\mathrm{W}=\mathrm{Q}_{1}-\mathrm{Q}_{2}$
(B) $\eta=\left(\mathrm{Q}_{2} / \mathrm{Q}_{1}\right)$
(C) $\eta=\left(\mathrm{W} / \mathrm{Q}_{1}\right)$
(D) $\eta=1-\left(\mathrm{Q}_{2} / \mathrm{Q}_{1}\right)$