Final answer:
The method that is not frequently employed by companies to encourage word-of-mouth is requiring customers to review their purchases.
Step-by-step explanation:
The method that is not frequently employed by companies to encourage word-of-mouth is B. requiring customers to review their purchases. While customer reviews can be valuable for building a company's reputation, they are not necessarily a direct method for encouraging word-of-mouth. Instead, companies often rely on strategies such as offering easily shareable content on social media, offering current customers incentives to refer new customers, asking for recommendations, and providing a consistently great product to encourage word-of-mouth.