An Office Building Janitorial Company Is Interested in the Opinions

Multiple Choice

An office building janitorial company is interested in the opinions of people who visit the office building on a typical day. He thinks that opinions of people who visit the office building in the morning could be different than those who visit later in the day and he does not want a biased sample. Which sampling method is likely to result in an unbiased sample?

A) A large sample of people who visit the building that have been stratified by age.
B) A cluster sample of all the people who visit the office building between 8:00 am and 9:00 am and between 5:00 pm and 6:00 pm.
C) A systematic sample of every tenth person who visits the office building throughout the day.
D) None of these.