It does not say that there is any contact between leaders and followers. It does say that the upper classes set the trend by buying and wearing the most *expensive* fashions available. The followers see the tend and if they like it or they have confidence that it will be the next trend, they buy into it. They are a very important group: they can deal with the cheaper lines and make a style more noticeable without paying the price that the trend setter would pay.
I think B is your best answer.
