A manager at a phone company wants to know if the company’s current customers would be interested in a new calling plan.

Which sampling method will most likely result in a biased sample?

An office assistant selects every 50th name on a customer list.

An office assistant selects the customers who call the office with questions about their current plan during one week.

An office assistant programs a computer to randomly select 500 customers from its database.

An office assistant divides the customers by time zone and randomly selects 100 customers in each zone.