A cybersecurity analyst is investigating an incident report concerning a specific user workstation. The workstation is exhibiting high CPU and memory usage, even when first started, and network bandwidth usage is extremely high. The user reports that applications crash frequently, despite the fact that no significant changes in work habits have occurred. An antivirus scan reports no known threats. Which of the following is the MOST likely reason for this?
A. Advanced persistent threat
B. Zero day
C. Trojan
D. Logic bomb