One of your Linux systems was compromised last night. According to change management history and a recent vulnerability

[answerhappygod]

One of your Linux systems was compromised last night. According to change management history and a recent vulnerability scan, the system's patches were up- to-date at the time of the attack. Which of the following statements is the Most Likely explanation?

A. It was a zero-day exploit.
B. It was a Trojan Horse exploit.
C. It was a worm exploit.
D. It was a man-in-middle exploit.