If $\mathrm{A}$ is a non-singular matrix satisfying $\mathrm{A}^{3}-7 \mathrm{~A}-6 \mathrm{I}=0$ then $\mathrm{A}^{-1}$ is given by
(a) $\frac{1}{6}\left(\mathrm{~A}^{2}-7 \mathrm{I}\right)$
(b) $\mathrm{A}^{2}-7 \mathrm{I}$
(c) $\frac{1}{6}\left(\mathrm{~A}^{2}+7 \mathrm{I}\right)$
(d) $\mathrm{A}^{2}+7 \mathrm{I}$