Similarly as in the previous problem

$\frac{1}{d}=\frac{1}{F}+\frac{1}{d^{\prime}}$

For maximum 'd', d' should be maximum i.e. $d^{\prime}=\infty$

Substituting $; \frac{1}{d}=\frac{1}{F}+\frac{1}{\infty} \Rightarrow d=f=10 \mathrm{~cm}$.

So, The correct option of this question is **(A).**