c
The matrix
$\left[ {\begin{array}{*{20}{c}}
1&a&b\\
c&1&d\\
e&f&1
\end{array}} \right]$
where exactly one of $a, b, c, d, e, f$ is $1$ and rest of them are zeros, is invertible. There are six such matrices.
Also, the matrix $\left[\begin{array}{lll}{1} & {0} & {1} \\ {0} & {1} & {0} \\ {1} & {0} & {0}\end{array}\right]$ is invertible.
Thus, there are at least $7$ such matrices which are invertible.