According to the 80/20 rule:

A、Only 80 percent of a company's customers deserve good service
B、20 percent of a company's customers produce 80 percent of the company's profit
C、20 percent of a company's customers should be classified as defect-prone
D、Only 80 percent of a company's customers will be affected by service encounters
E、20 percent of a company's customers will require little or no service