Explanation:

Let’s break down what each option actually means:

- Sale: This is when someone gives up ownership of a good or property in exchange for money. It's about selling, not just handing something over.

- Purchase: The opposite side of a sale, when someone buys something and takes ownership. It’s about acquiring, not passing something along.

- Delivery: This is the one you want. Delivery means moving possession of an item from one person to another, willingly. It doesn’t matter if there’s money or not; it’s just about the act of handing something over on purpose.

- Exchange: Here, two people swap goods or services. Both sides give and get, so it’s not just about simple transfer of possession.