Answer: The correct answer is Green because it has lea volume and more amount of matter.
Explanation: Density of an object is defined as the amount of matter that can be stored in a unit volume.
Mathematically,

An object will be more dense, if it has less volume and has more amount of matter.
And an object will be less dense if it has more volume and has less amount of matter.
We are given two cubes. Volume of the cube is calculated by using the formula:

where, a = side of the cube
Red: The side of this cube is 4 and volume will be =

Green: The side of this cube is 3 and volume will be =

As, the volume of Green cube is less. So, this cube will be more denser.
Conclusion: The correct answer is Green because it has lea volume and more amount of matter.