Answer:

The cabinet full of books.

Explanation:

This is because the wheels on the rollers can move freely, making the frictional force decrease. For the bookshelf full of books, it will be hard because the bookshelf is full of books, making the frictional force increase.

(Frictional force is a type of force that stops a thing from moving unless there's a push or pull force applied to it.)

Hope this helps!