Answer
$A$ is not an invertible matrix.
(Th.8, (a) and (b))
Work Step by Step
The second column of A has all zero entries, so A can not row-reduce to I
So, looking at Th.8,
$\mathrm{b}. \quad A$ is row equivalent to the $n\times n$ identity matrix..
is not valid. Then,
$\mathrm{a}. \quad A$ is an invertible matrix.
is not valid as well
$A$ is not an invertible matrix.
(Th.8, (a) and (b))