$1$ point

Viral marketing refers to:

a digitally enabled promotional strategy that encourages individuals to forward marketerinitiated messages to others via email, social networking, and blogs.

a subversive program that automatically transfers viruses from one website to another.

malicious malware that is used to create doppelgangers on competitors' websites.

an embedded message that causes a pop$-$up screen to appear every time a user types in a specific word.