An espresso coffee franchise is considering expanding its services to a new location in the city, but prior to doing so it will use a survey to determine the extent to which its customers are interested in a second location. Which of the following procedures would be most appropriate for obtaining a statistically unbiased sample?

A. Survey a selection of people whose names are randomly chosen from the telephone directory for the city.

B. Ask customers who drive through to voluntarily phone in their preferences.

C. Ask customers who drive through to voluntarily mail in their preferences.

D. Survey a selection of people whose names are randomly chosen from a list of all customers.