Which of the Following Choices Most Accurately Describes an Example

Which of the following choices most accurately describes an example of the echo chamber?

A) An individual relies on the Facebook newsfeed for information about an upcoming election.
B) A firm uses Twitter to attract and advertise to potential new customers.
C) A firm deletes all reviews and comments from their website after fourteen days.
D) A firm uses a celebrity to advertise and promote their brand and products.