The area of the greatest circle which can be inscribed in a square whose perimeter is 120 cm, is :

Answer: Option D

Side of the square :
$$\begin{array}{rl}& =\frac{120}{4}cm\\ & =30cm\end{array}$$
Radius of the required circle :
$$\begin{array}{rl}& =\left(\frac{1}{2}\times 30\right)cm\\ & =15cm\\ & =\pi \times r^2\\ & =\left[\frac{22}{7}\times {\left(15\right)}^2\right]c{m}^2\end{array}$$