A market research firm calls a simple random sample of customers to determine whether they are satisfied with their current internet service provider. Out of 500 people surveyed, 389 say they are satisfied. If we are going to make a confidence interval for the percent of customers in the population who are satisfied, we will need a box model. Fill in the blank: The number of tickets in the box labeled 1 is a quantity that is _______.

A) fixed and known

B) fixed and estimated

C) random and known

D) random and estimated