(c)
Plane meets axes at $A(2,\ 0,\ 0),\ B(0,\ 3,\ 0)$ and $C(0,\ 0,\ 6)$
Then area of $\mathrm{\Delta}ABC$ is
$\frac{1}{2}\left| \overrightarrow{AB} \times \overrightarrow{AC} \right|$
$= \frac{1}{2}\left| \left( - 2\widehat{i} + 3\widehat{j} \right) \times \left( - 2\widehat{i} + 6\widehat{j} \right) \right|$
$= 3\sqrt{14}\ \ \$sq units