While browsing a website, a staff member received a message that the website could not be trusted. Shortly afterward, several other colleagues reported the same issue across numerous other websites. Remote users who were not connected to corporate resources did not have any issues. Which of the following is MOST likely the cause of this issue?


A. A bad antivirus signature update was installed.
B. A router was misconfigured and was blocking traffic.
C. An upstream internet service provider was flapping.
D. The time or date was not in sync with the website.