Magnification of a compound microscope is $30$. Focal length of eyepiece is $5\text{cm}$ and the final image is formed at the least distance of distinct vision. Find the magnification of objective lens.

The correct option is A $5$
Given:

$m=30$
$f_e=5\text{cm}$

Magnification of the compound microscope when the final image is formed at the least distance of distinct vision is given by,

$m=\frac{v_o}{|u_o|}(1+\frac{D}{f_e})$

$\Rightarrow 30=m_o(1+\frac{25}{5})$

$\Rightarrow m_o=5$

Hence, option $\left(A\right)$ is the correct answer.