Inertia describes which of the following? how long an object is how large an object is how difficult it is to change an object's motion how fast an object is moving

How difficult it is to change an objects motion. Think of a tablecloth; it takes energy to move it from underneath objects on the table, and it takes energy to move the objects themselves on the table.

Sorry I'm late.
Here is an example:
I have two equal bricks, with the difference of material.
One is foam and the other is cement.
If I give both an equal push which one would be easier to push?
The foam brick because it has less inertia. The more inertia the more resistance you will have, just like the cement brick. So the answer would be "How difficult it is to change an object's motion."

True, the standard unit for volume is liters which can be represented by either a lower case "l" or a capital "l"