Rixton Inc, with the support of Ad360, unveils its new mobile phone using a variety of advertising techniques. Later, Rixton Inc conducts a survey and finds that 70 percent of the customers bought the phone because of their friends' suggestions

In this case, what does this survey show? How can this type of behavior be explained?
a) Word-of-mouth public relations and viral marketing campaigns are crucial. This can be explained because customers preferred a personal recommendation from someone they know and trust.
b) Longer and in-depth articles pay a key role in marketing campaigns. This can be explained because customers were influenced by the wide range of information that was made available to them.
c) Longer and in-depth articles pay a key role in marketing campaigns. This can be explained because customers were influenced by the personal views of the experts.
d) Word-of-mouth public relations and viral marketing campaigns are crucial. This can be explained because customers were more influenced by the mass media than their friends and colleagues.

a