Final answer:
Mary, who uses computers and the internet to launch attacks against computer systems for political or ideological reasons, is considered a Hacker.
Step-by-step explanation:
Mary, who uses computers and the internet to launch attacks against computer systems for political or ideological reasons, is considered a Hacker. A hacker is someone with advanced technical skills who gains unauthorized access to computer systems. In this case, Mary's actions are illegal and unethical. The term "hacker" is often used broadly to describe individuals who gain unauthorized access to computer systems or networks for various reasons, including political or ideological motivations. The other terms (Vigilante, Crusader, Extremist) may have different connotations and are not specifically associated with the act of exploiting computer systems for political or ideological purposes.