Answer:
The correct answer is - the rocks are more compact and have more mass per unit volume.
Explanation:
The density of a substance is a degree of their compactness or how closely their molecules are packed in it. The density can be explained as the mass of the substance of in it per unit volume.
The water and air are less compact or have less mass in every unit volume area in comparison to the rock as it is more compact and dense. It can be derived by the mass of the substance divided by the volume of the substance.
Thus, the correct answer is - the rocks are more compact and have more mass per unit volume.