Find the Inverse of the Matrix $$\left[ \begin{array} { c c c } 7 & 7 & 7 \\21 & 35 & 28 \\21 & 42 & 35\end{array} \right]$$

Multiple Choice

Find the inverse of the matrix $$\left[ \begin{array} { c c c } 7 & 7 & 7 \\21 & 35 & 28 \\21 & 42 & 35\end{array} \right]$$ . ​

A) ​ $$\frac { 1 } { 7 } \left[ \begin{array} { c c c } 1 & 1 & - 1 \\- 3 & 2 & - 1 \\3 & - 3 & 2\end{array} \right]$$
B) ​ $$\frac { 1 } { 7 } \left[ \begin{array} { c c c } 1 & 1 & 1 \\0 & - 2 & - 1 \\3 & - 3 & 2\end{array} \right]$$
C) ​ $$- 7 \left[ \begin{array} { c c c } 3 & 1 & 0 \\- 3 & 1 & - 1 \\1 & - 3 & 2\end{array} \right]$$
D) ​ $$- \frac { 1 } { 7 } \left[ \begin{array} { c c c } 1 & 0 & - 1 \\- 3 & 2 & - 1 \\2 & - 3 & 3\end{array} \right]$$
E) ​ $$7 \left[ \begin{array} { c c c } 1 & 1 & 1 \\- 3 & 0 & - 1 \\3 & - 3 & 2\end{array} \right]$$