Which of the following matrices can NOT be obtained from the matrix $\left[\begin{array}{cc}-1& 2\\ 1& -1\end{array}\right]$ by asingle elementary row operation? 

$$\begin{gathered} \mathrm{A}=\left[\begin{array}{cc}-1& 2\\ 1& -1\end{array}\right] \\ \left(1\right){\mathrm{R}}_1\to {\mathrm{R}}_1+{\mathrm{R}}_2;\left[\begin{array}{cc}0& 1\\ 1& -1\end{array}\right] \mathrm{possible} \\ \left(2\right) {\mathrm{R}}_1\leftrightarrow {\mathrm{R}}_2;\left[\begin{array}{lc}1& -1\\ -1& 2\end{array}\right] \mathrm{possible} \\ \left(3\right)\mathrm{Option} \mathrm{is} \mathrm{not} \mathrm{possible} \\ \left(4\right) {\mathrm{R}}_2\to {\mathrm{R}}_2+2{\mathrm{R}}_1;\left[\begin{array}{l}-1\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}2\\ -1\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}\hspace{0.25em}3\end{array}\right] \mathrm{possible} \end{gathered}$$