Final Answer:
Salespeople are considered knowledge workers primarily because they gain knowledge of the product before they can sell it, as indicated by option B.
Step-by-step explanation:
Knowledge workers are individuals who use their intellect and expertise to perform their jobs effectively. In the context of sales, option B correctly identifies salespeople as knowledge workers because they acquire in-depth knowledge of the products or services they are selling. This knowledge is crucial for understanding customer needs, addressing inquiries, and positioning the product effectively. While options A and D also touch on aspects of knowledge work in sales, the key characteristic defining salespeople as knowledge workers is their comprehensive understanding of the products they sell.
Option B is the answer.