Kofi wants to find the most-liked snacks to put in the vending machine at his office so the most people will buy from it. Which of the following strategies would help Kofi ensure a random sample?

A. He could survey the first ten people who use the vending machine on a Monday morning.

B. He could survey the employees who do not buy snacks from the vending machine.

C. He could make an alphabetical list of employees in his office and survey every third employee.

D. He could make an alphabetical list of employees in his office and survey the first ten employees.