Using a refill pen can reduce what?

Correct answer: Plastic and waste

The governing concept is reuse and waste prevention. A refill pen has a durable outer body that remains in use, while only the empty ink refill is replaced. If a person buys a completely new disposable pen every time the ink ends, more plastic bodies, packaging, and discarded parts may be produced. Replacing only the refill can therefore reduce the amount of plastic used and the quantity of solid waste generated, although the exact saving depends on the product and how it is used. Study and knowledge are not reduced by the pen, and tree shade has no relevant connection. Thus, option B is correct.