Robert works for an electronics firm that sells cellular phones. Robert sells only V-Techs, a certain type of cellular phone, to distributors across the United States. Because of the specialized knowledge Robert must learn to sell the V-Techs, that is the only type of phone Robert sells. Robert's firm organizes its sales force by:

Robert's firm organizes its sales force by product line.

Explanation:

When a company organizes it's force by product line, every sales team or representative will be in charge of the sales of a specific product; this is a benefit for the sellers because they just need to promote one type of product. It allows them to specialize in the product features and specific commercial activities to increase the sales results, including merchandising, advertising and personal promotion. Robert will be learning and creating strategies for the promotion of V-Techs and other workers will be doing the same with other types of cellular phones.