Find the Characteristic Equation of the Given Matrix $$A = \left[ \begin{array} { r r r r } 9 & 6 & 4 & 3 \\0 & 7 & - 6 & 8 \\0 & 0 & 5 & 9 \\0 & 0 & 0 & 9\end{array} \right]$$

Multiple Choice

Find the characteristic equation of the given matrix.
- $$A = \left[ \begin{array} { r r r r } 9 & 6 & 4 & 3 \\0 & 7 & - 6 & 8 \\0 & 0 & 5 & 9 \\0 & 0 & 0 & 9\end{array} \right]$$

A) $( 9 - \lambda ) ^ { 2 } ( 7 - \lambda ) ( 5 - \lambda ) = 0$
B) $( 9 - \lambda ) ( 6 - \lambda ) ( 4 - \lambda ) ( 3 - \lambda ) = 0$
C) $( 9 - \lambda ) ( 7 - \lambda ) ( 5 - \lambda ) = 0$
D) $( 9 - \lambda ) ( 9 - \lambda ) ( 8 - \lambda ) ( 3 - \lambda ) = 0$