A technician just installed an antivirus suite on a workstation. It is kept up-to-date and has recently scanned the system. A day later the user reports slower response times than usual. Which of…

Advertisements are associated with adware or browser hijackers, which were not introduced in this scenario - a legitimate antivirus suite was installed.

Antivirus suites run background processes including real-time file system monitors, scheduled full scans, and definition update services that continuously consume CPU cycles and memory. This resource consumption is expected behavior and is the most likely cause of slower performance immediately after a fresh install with an up-to-date scan completing.

A trojan infection is unlikely because the antivirus was just installed, kept up-to-date, and completed a recent scan without presumably finding a threat.

Unremoved viruses would imply the antivirus scan failed to detect an active infection, which is possible but far less likely than the expected overhead of the antivirus software itself.