Question

the amount of space an object occupies is its: * mass density volume luminosity

Explanation:

Mass is the amount of matter in an object. Density is mass per unit volume ($\text{density}=\frac{\text{mass}}{\text{volume}}$). Luminosity is the total amount of energy emitted by an object (like a star) per unit time. Volume is defined as the amount of space an object occupies.

Answer:

volume