The identity element in the group M = \(\left\{ {\left( {\begin{array}{*{20}{c}} {\rm{x}}&{\rm{x}}\\ {\rm{x}}&{\rm{x}} \end{array}} \right);{\rm{x}} \in \,{\rm{R}}\,;{\rm{x}} \ne 0} \right\}\) with respect to matrix multiplication is
1
\(\left( {\begin{array}{*{20}{c}} 1&1\\ 1&1 \end{array}} \right)\)
2
\(\frac{1}{2}\left( {\begin{array}{*{20}{c}} 1&1\\ 1&1 \end{array}} \right)\)
3
\(\left( {\begin{array}{*{20}{c}} 1&0\\ 0&1 \end{array}} \right)\)
4
\(\left( {\begin{array}{*{20}{c}} 0&1\\ 1&0 \end{array}} \right)\)