Which of the Following Defines a Rootkit

Multiple Choice

Which of the following defines a rootkit?

A) It is the act of fraudulently using email to try to get the recipient to reveal personal data by sending legitimate-looking emails urging the recipient to take action to avoid a negative consequence or to receive a reward.
B) It is the unintended release of sensitive data by unauthorized individuals.
C) It is the abuse of email systems to send unsolicited email to large numbers of people.
D) It 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.