Ans: A
$\begin{array}{cl}
& 3m^2 – 5mn +2n^2 +m -n \\
= & (3m-2n)(m-n) + ( m-n) \\
= & (m-n)(3m-2n+1)
\end{array}$
$\begin{array}{cl}
& 3m^2 – 5mn +2n^2 +m -n \\
= & (3m-2n)(m-n) + ( m-n) \\
= & (m-n)(3m-2n+1)
\end{array}$
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