Final answer:
The 1000g mass has the greatest inertia.
Step-by-step explanation:
The mass of an object determines its inertia, which is the resistance of an object to changes in its motion. In this case, we are comparing the masses of different objects to determine which one has the greatest inertia. In general, the greater the mass of an object, the greater its inertia. So, the mass with the greatest inertia would be the 1000g mass.