Find the null space for $A = \left[\begin{matrix} 2 & 1 & -4 \cr -5 & 4 & -3 \cr 7 & 1 & -9\cr \end{matrix}\right].$

What is null$(A)$?

A. span$\left\{\left[\begin{matrix} 2 \cr 1 \cr -4 \cr \end{matrix}\right]\right\}$
B. span$\left\{\left[\begin{matrix} 1 \cr 2 \cr 1 \cr \end{matrix}\right]\right\}$
C. span$\left\{\left[\begin{matrix} 0 \cr 0 \cr 0 \cr \end{matrix}\right]\right\}$
D. span$\left\{\left[\begin{matrix} 2 \cr -5 \cr 7 \cr \end{matrix}\right]\right\}$
E. span$\left\{ \left[\begin{matrix} 2 \cr 1 \cr -4 \cr \end{matrix}\right], \left[\begin{matrix} -5 \cr 4 \cr -3 \cr \end{matrix}\right] \right\}$
F. ${\mathbb R}^3$
G. none of the above
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