Why Do Many Brands with a Large Market Share Spend

Why do many brands with a large market share spend proportionally less on advertising compared to brands with small market share?

A) Beyond a certain volume of promotion,diminishing returns set in.
B) Certain industries have a practice of spending a low amount of dollars,relative to sales,on advertising.
C) There is no minimum level of exposure for advertising to have an effect on sales.
D) Advertising will not stimulate economic growth for the industry.
E) The firms with large market share do not have to advertise anymore.