Efficiency of a Carnot engine working between temperatures T1 and T2 (T1 < T2) is

Answer: Option A

Here the question should be read carefully given $$\left(T_1<T_2\right)$$
So, the hot reservoir is $$T_2$$ and cold reservoir is $$T_1$$ hence the efficiency will be $$\aleph =1-\frac{T_1}{T_2}$$