Augustus, a student undergoing his doctorate program, is working on a thesis that requires him to browse the Internet for information and visit various unverified websites. To protect his computer from the risk of attracting unwanted messages and other security threats, he uses a tool that uses both hardware and software to provide protection against hackers. In the given scenario, Augustus is most likely using $\_\_\_\_\_.$

Group of answer choices

spyware

malware

a spam filter

a firewall