Churn rate is a term that refers to the:

Select one:

a$.$ average number of recommended titles in a user's queue.

b$.$ rate at which customers leave a product or service.

c$.$ number of movie titles that are difficult to assign reliable user ratings.

d$.$ number of new users that each existing user attracts through word$-$of$-$mou social sharing.

e$.$ rate at which the demand for a product or service fluctuates with price cha