If $\alpha, \beta, \gamma$ are the roots of $x^3+2x^2-3x-1=0$, then $\alpha^{-2}+\beta^{-2}+\gamma^{-2}=$

Question

\[\begin {array} {1 1} (a)\;12 & \quad (b)\;13 \\ (c)\;14 & \quad (d)\;15 \end {array}\]