要使 $\boldsymbol{\xi}_{1}=\left(\begin{array}{l}1 \\ 0 \\ 2\end{array}\right), \boldsymbol{\xi}_{2}=\left(\begin{array}{c}0 \\ 1 \\ -1\end{array}\right)$ 都是线性方程组 $\boldsymbol{A x}=\mathbf{0}$ 的解, 只要系数矩阵 $\boldsymbol{A}$ 为 ( )
A. $(-2,1,1)$.
B. $\left(\begin{array}{ccc}2 & 0 & -1 \\ 0 & 1 & 1\end{array}\right)$.
C. $\left(\begin{array}{ccc}-1 & 0 & 2 \\ 0 & 1 & -1\end{array}\right)$.
D. $\left(\begin{array}{ccc}0 & 1 & -1 \\ 4 & -2 & -2 \\ 0 & 1 & 1\end{array}\right)$.