c
(c) Let $A = \left[ {\begin{array}{*{20}{c}}3&{ - 2}&{ - 1}\\{ - 4}&1&{ - 1}\\2&0&1\end{array}} \right]$,
then $|A| = \left| {\,\begin{array}{*{20}{c}}3&{ - 2}&{ - 1}\\{ - 4}&1&{ - 1}\\2&0&1\end{array}\,} \right| = 1$
The matrix of cofactors of $ A$
= $\left[ {\begin{array}{*{20}{c}}{{c_{11}}}&{{c_{12}}}&{{c_{13}}}\\{{c_{21}}}&{{c_{22}}}&{{c_{23}}}\\{{c_{31}}}&{{c_{32}}}&{{c_{33}}}\end{array}} \right] = \left[ {\begin{array}{*{20}{c}}1&2&{ - 2}\\2&5&{ - 4}\\3&7&{ - 5}\end{array}} \right]$
Therefore, $adj(A) = \left[ {\begin{array}{*{20}{c}}1&2&3\\2&5&7\\{ - 2}&{ - 4}&{ - 5}\end{array}} \right]$
$\therefore $ ${A^{ - 1}} = \frac{1}{{|A|}}\,.\,adjA = \left[ {\begin{array}{*{20}{c}}1&2&3\\2&5&7\\{ - 2}&{ - 4}&{ - 5}\end{array}} \right]$ ,$\because \,|A| = 1$