Answer
Store B is selling the product for a cheaper price.
Work Step by Step
There are a number of reasons that Store B sales could have surpassed the sales of Store A, including customer service, marketing, and store size. One of the more likely reasons is that Store B found a way to offer a comparable or better product at the same price. After all, with wireless headphones, consumers don't tend to by as loyal to the store but rather are concerned about the amount of sound quality they can get for the given price.
