Volume of Shape A is the volume of Shape B, given each cube inside each shape is of 1 cubic unit.

The correct option is B less than
Shape A:


Volume of base area
= $4\times 3\times 1\text{cu units}$
= $12\text{cu units}$

Number of layers = 2

Therefore, total volume
$=\text{Volume of the base area}\times \text{Number of layers}$
$=12\times 2\text{cu units}$
$=24\text{cu units}$


Shape B:



Volume of base area
$=4\times 2\times 1\text{cu units}$
$=8\text{cu units}$

Number of layers = 4

Therefore, total volume
$=\text{Volume of the base area}\times \text{Number of layers}$
$=8\times 4\text{cu units}$
$=32\text{cu units}$

∴ Volume of Shape A is less than volume of Shape B.