Which of the following are ways in which a geologist may determine the density of earth materials?

A) determining the weight of the object, but not its volume
B) calculating the volume of the object, but not its mass
C) none of these

Determining the density of earth materials requires both the mass (or weight) and the volume of the object. Neither determining the weight alone nor calculating the volume alone is sufficient to determine density. Density is calculated as mass divided by volume.