Let $\mathrm{A}=\left(\begin{array}{ccc}1 & -1 & 0 \\ 0 & 1 & -1 \\ 1 & 1 & 1\end{array}\right), \mathrm{B}=\left(\begin{array}{l}2 \\ 1 \\ 7\end{array}\right)$ Then for the validity of the result $\mathrm{AX}=\mathrm{B}, \mathrm{X}$ is

• A

  $\left(\begin{array}{c}-1 \\ 1 \\ 7\end{array}\right)$
• B

  $\left(\begin{array}{l}1 \\ 2 \\ 4\end{array}\right)$
• C

  $\left(\begin{array}{c}3 \\ 1 \\ -1\end{array}\right)$
• Correct answer
  D

  $\left(\begin{array}{l}4 \\ 2 \\ 1\end{array}\right)$

Hence, the correct answer is option: 'D'.