Which of the Following Is Stated by the Long Tail

Which of the following is stated by the long tail phenomenon?

A) When production is increased by 80 percent, the decrease in cost is close to 20 percent due to economies of scale.
B) To gain a competitive advantage, it is necessary for a business to internalize 80 percent of its R&D, and outsource the remaining 20 percent.
C) For an incumbent firm, 80 percent of its revenue comes from existing customers, and new customers account for the remaining 20 percent.
D) Almost 80 percent of sales in a given product category come from only 20 percent of the offerings in that category.