b
Determinant value of matrix
$=1-\mathrm{wc}-\mathrm{aw}+\mathrm{w}^{2} \mathrm{ac}=0$
$\Rightarrow(1-\mathrm{aw})(1-\mathrm{wc})=0$
$a=\frac{1}{w}=w^{4} \Rightarrow b$ and $c$ each have $4$ and $4$ options.
if $\mathrm{c}=\frac{1}{\mathrm{w}}=\mathrm{w}^{4}$ and $\mathrm{a} \neq \mathrm{w}^{4}$
$\Rightarrow$ $a$ have $3$ and $b$ have $4$ options.
$\therefore $ Total matrices $=4 \times 4+3 \times 4=28$