2026/024) Which of the following numbers is a perfect square? A) $\frac{14!15!}{2}$, B) $\frac{15!16!}{2}$,C) $\frac{16!17!}{2}$,D) $\frac{17!18!}{2}$

 

We are having numbers in the form $\frac{n!(n+1)!}{2}$ .

This is $\frac{(n!)^2 * (n+1)}{2}$

It  is a perfect square if $\frac{(n+1)}{2}$ is a perfect square $\frac{18}{2}$ is a perfect square so (D) is the answer