An object is present on the principal axis of a concave mirror at a distance 30 cm from it. Focal length of the mirror is 20cm. Image formed by mirror is:

Use the direct correlation between image distance, object distance, and focal length in this question, which is $\frac{1}{v}+\frac{1}{u}=\frac{1}{f}$, Finding the image distance for the concave mirror will be aided by a straight replacement of the variables.

Object distance $\mathrm{u}=-30 \mathrm{cm}$
length of the mirror's focus $f=-20 \mathrm{cm}$
Using mirror formula $\frac{1}{\mathrm{v}}+\frac{1}{\mathrm{u}}=\frac{1}{\mathrm{f}}$
$\therefore \frac{1}{\mathrm{v}}+\frac{1}{-30}=\frac{1}{-20}$
$\Rightarrow \mathrm{v}=\frac{\left(30\right)\left(20\right)}{-30+20}=-60 \mathrm{cm}$

As a result of the negative image distance, an image is created in front of the mirror at a distance of 60 cm.

Hence, the correct answer is option A.