Andrea receives an e-mail from her sister-in-law that is actually a recommendation for a website with a demonstration of a new home hair-coloring system. She later discovers that her sister-in-law received a free trial kit for passing Andrea's and four other friends' e-mail addresses along to the marketer. This is known as
a) viral marketing.
b) buzz marketing.
c) guerilla marketing.
d) a word-of-mouth pyramid.
e) personal advertising.
Answer: a) viral marketing.