Answer:
The correct answer is letter "B": spotters.
Step-by-step explanation:
Spotters are individuals who act on behalf of a business without the need of being employees. Usually, the company engages in a regular sale relationship with these individuals and offers them rewards -in the form of discounts, for instance- in exchange for promoting the benefits of certain products or referring other potential buyers.
Spotters use word-to-mouth marketing to promote an entity.