I have updated the explanation.
almalikrajpari
I don't really agree with C as the answer.
Rationale: 'Premium watch buyers' are already a subset of the population and only some of those buyers, which is a subset of a subset and hence how will that help in increasing the sales?
Thank you for the feedback but I am afraid you are confusing the question types. This is not a must be true question. The burden of proof for explain questions is much lower. We do not have to prove that the situation will always result into a certain outcome. Instead, in this question type, the explanation has to only work in some cases. That's all.
This answer choice is reasonable - there are some people who look for premium watches that are exclusive who previously did not consider this brand, and now they are considering it. If this group of people outnumbers the people who are not turned off by the higher price, this could result into greater sales. (how big is this group, how many watches they sell per year - 10 or 10,000 - we do not know, but we don't need to because the explanation has to only work some times)
Since this answer choice provides a possible explanation to the paradox in even 1% of the cases, and all other choices are clearly wrong. Then this choice is the BEST explanation. It meets the criteria that this is possible and this is the ONLY possible case.
P.S. This is the easiest question we have on
GMAT Club tests by the way - almost everyone has answered it correctly.