____ is the percentage of a company's customers (for a given span of time) who by the end of that time span can no longer be considered customers of the company (e.g., because they have cancelled their contract for a service or they have stopped shopping at the related retail location).
A.
Cost per click
B.
Conversion
C.
Return on investment (ROI)
D.
Churn rate
E.
Cost per order
Answer: Churn rate