Calculate the width of the rectangular prism if its volume is 128 cu units.

The correct option is C 4 units
Volume of a rectangular prism
= length $\times$ width $\times$ height
= 8 $\times$ w $\times$ 4
= 32w cu units

But, volume = 128 cu units.

$\therefore$ 32w = 128
$⟹$ w = $\frac{128}{32}=4$ units

Hence, the width of the rectangular prism is 4 units.