Volume of the above rectangular prism is cu units, when the volume of each cube inside is 1 cu unit.

The correct option is A 27
Consider the base layer:


There are 3 cubes along the length and 3 cubes along the width.

Volume of 1 unit cube = 1 cubic unit.

∴ Volume of the base layer is
$=3\times 3\times \text{1 cubic unit}$
= 9 cubic units.

Now consider the height:


There are 3 layers.

Therefore, the volume of the shape
$=\text{volume of the base layer}\times \text{number of layers}$
$=9\times 3\text{cubic units}$
= 27 cubic units.