b
(b) $A = \left[ {\,\begin{array}{*{20}{c}}1&2\\3&{ - 5}\end{array}\,} \right]$
$adj\,A = \left[ {\,\begin{array}{*{20}{c}}{ - 5}&{ - 2}\\{ - 3}&{ + 1}\end{array}\,} \right]$
$|A| = \left| {\,\begin{array}{*{20}{c}}1&2\\3&{ - 5}\end{array}\,} \right| = - 11$
$\therefore \,\,{A^{ - 1}} = \frac{1}{{11}}\left[ {\,\begin{array}{*{20}{c}}5&2\\3&{ - 1}\end{array}\,} \right] = \left[ {\,\begin{array}{*{20}{c}}{5/11}&{2/11}\\{3/11}&{ - 1/11}\end{array}\,} \right]$.