Final answer:
The practice of selling a printer to a customer who has already bought a desktop computer is called cross-selling, which aims to add value to the customer's purchase and increase sales. The option (D) is correct.
Step-by-step explanation:
Selling a printer to a customer who has bought a desktop computer is an example of cross-selling. This sales strategy involves offering additional, related products or services to an existing customer during the sales process. Cross-selling typically aims to increase the value of a sale and improve customer satisfaction by providing a comprehensive solution.
For example, when a customer purchases a desktop computer, suggesting a compatible printer or selling additional software relevant to their needs are both cross-selling opportunities that can enhance their overall experience and the utility of the purchase. Therefore, option (D) is correct.