Which of the following is true of spam? select one: 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.