With regard to customer defection, which of the following statements is incorrect?

A、Defection rates are determined by customer loyalty.;
B、The longer a company holds on to a customer, the greater is the volume of customer-generated unit sales.;
C、Lowering customer defection rates creates a higher cost structure.;
D、The longer a company retains a customer the higher the average unit cost of each sale.;
E、There is a positive relationship between the length of time that a customer stays with the company and profit per customer.