What Does the Phrase "Hearing the Voice of the Consumer

What does the phrase "hearing the voice of the consumer" mean?

A) Companies have the information they need to effectively satisfy wants and needs in the marketplace.
B) Companies specifically use telemarketing to hear their customers' opinions.
C) Marketing is carried out for the benefit of the customers.
D) Marketing managers should take the time to listen in on focus groups.
E) Market trials are necessary for certain products.