Which one of the following matrices is an elementary matrix?

• A. \(\left[ {\begin{array}{*{20}{c}} 1&0&0\\ 0&0&0\\ 0&0&1 \end{array}} \right]\)
• B. \(\left[ {\begin{array}{*{20}{c}} 1&5&0\\ 0&1&0\\ 0&0&1 \end{array}} \right]\)
• C. \(\left[ {\begin{array}{*{20}{c}} 0&2&0\\ 1&0&0\\ 0&0&1 \end{array}} \right]\)
• D. \(\left[ {\begin{array}{*{20}{c}} 1&0&0\\ 0&1&0\\ 0&5&2 \end{array}} \right]\)