An object is placed symmetrically between two plane mirrors inclined at an angle of ${72}^{\circ }$, then the total number of images observed will be

The correct option is B $4$

Hence total number of images formed will be $4$.

Alternative:
Given:
Angle between the mirrors, $\theta ={72}^{\circ }$
So, $n=\frac{{360}^{\circ }}{\theta }=\frac{{360}^{\circ }}{{72}^{\circ }}=5$
As $n$ is odd and object is placed symmetrically, hence, the number of images,
$=n-1=5-1=4$