Answer: Block A has the greatest density.
Step-by-step explanation:
Density is defined as the mass contained per unit volume.

To calculate the volume of cuboid, we use the equation:
where,
V = volume of cuboid
l = length of cuboid
b = breadth of cuboid
h = height of cuboid
Putting values in above equation, we get:
a) Block A:
mass = 3 kg
Volume =

b) Block B:
mass = 1 kg
Volume =

c) Block C:
mass = 2 kg
Volume =

Thus Block A has greatest density.