Which of the Following Is True of Spam

Which of the following is true of spam?

A) Spam is a type of attack with which a hacker takes over computers via the Internet and causes them to flood a target site with demands for data and other small tasks.
B) Spam is a program in which malicious code is hidden inside a seemingly harmless program.
C) Spam is a set of programs that enables its user to gain administrator-level access to a computer without the end user's consent or knowledge.
D) Spam is an extremely inexpensive method of marketing used by many legitimate organizations.