The volume of the cuboid as shown below is cu in.

The correct option is D $\frac{9}{8}$
From the given image,

$\text{Length}=3\text{in}$
$\text{Width =}\frac{1}{2}\text{in}$
$\text{Height =}\frac{3}{4}\text{in}$

We know,
Volume of cuboid = length x width x height
$=3\times \frac{1}{2}\times \frac{3}{4}$
$=\frac{9}{8}\text{cu in}$