Which Matrix Indicates That the Equations of Its Associated System $\left[ \begin{array} { c c : c } 1 & - 9 & 5 \\0 & 1 & 1\end{array} \right]$

Multiple Choice

Which matrix indicates that the equations of its associated system of equations has infinitely many solutions?

A) $\left[ \begin{array} { c c : c } 1 & - 9 & 5 \\0 & 1 & 1\end{array} \right]$
B) $\left[ \begin{array} { c c : c } 1 & - 9 & 5 \\0 & 0 & 6\end{array} \right]$
C) $\left[ \begin{array} { c c : c } 1 & - 2 & 3 \\0 & 0 & 0\end{array} \right]$
D) $\left[ \begin{array} { l l : l } 1 & 0 & 5 \\0 & 1 & 1\end{array} \right]$