Which of the Following Is an Approach to Viral Marketing

Which of the following is an approach to viral marketing?

A) embed a message in the product or service so that customers hardly realize they are passing it along
B) use customerization to impact customer satisfaction
C) employ choiceboards to allow consumers an easy way to share information
D) use niche marketing to attract customers that are likely to be opinion leaders
E) use permission marketing to avoid sending commercial messages to those who do not want them