Final answer:
The measure of density among the given values is '6.8 g/cm³'. It is the only option that represents the mass per unit volume, which is how density is defined.
Step-by-step explanation:
The value that represents a measure of density is '6.8 g/cm³'. Density is the ratio of the mass of a substance to its volume. The SI unit of density is kilograms per cubic meter (kg/m³), but for practical purposes, especially when dealing with solids and liquids, density is commonly measured in grams per cubic centimeter (g/cm³).
For example, the density of water is conveniently 1 g/cm³, which can be used as a reference point. This means that 1 g/cm³ is equal to 1000 kg/m³; thus, densities of most liquids and solids range from about 0.7 g/cm³ to 19 g/cm³. The value 6.8 g/cm³ refers to the density of a substance, revealing its mass per unit volume in the metric system.