$\begin{array}{1 1}
(A) I=\bigg(\large\frac{1}{n+1}-\frac{1}{n+2}\bigg)
\\ (B) I=\bigg(\large\frac{1}{n-1}-\frac{1}{n-2}\bigg)
\\ (C) I=\bigg(\large\frac{1}{n+2}-\frac{1}{n+1}\bigg) \\
(D) I=\bigg(\large\frac{1}{n+1}+\frac{1}{n+2}\bigg)
\end{array} $