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For \( 2 \leq \mathrm{r} \leq \mathrm{n},\left(\begin{array}{l}\mathrm{n} \\ \mathrm{r}\end{array}\right)+2\left(\begin{array}{c}\mathrm{n} \\ \mathrm{r}-1\end{array}\right)+\left(\begin{array}{c}\mathrm{n} \\ \mathrm{r}-2\end{array}\right)= \)
\( \mathrm{P} \)
(A) \( \left(\begin{array}{l}\mathrm{n}+1 \\ \mathrm{r}-1\end{array}\right) \)
(B) \( 2\left(\begin{array}{l}\mathrm{n}+1 \\ \mathrm{r}+1\end{array}\right) \)
(C) \( 2\left(\begin{array}{c}\mathrm{n}+2 \\ \mathrm{r}\end{array}\right) \)
(D) \( \left(\begin{array}{c}\mathrm{n}+2 \\ \mathrm{r}\end{array}\right) \)
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