What Would Be an Example of Increased Productivity of Capital

What would be an example of increased productivity of capital?

A) A potter's workshop starts paying for itself when the potter begins to sell finished pieces.
B) A new piece of architectural software gets more use as workers gradually get familiar with it.
C) A forklift moves more pieces per hour when there is a more experienced operator at the wheel.
D) A new automated lathe performs the same jobs faster than the older model did.
E) A commercial truck uses less diesel fuel after a tune-up than it did before.