Correct Answer. C. There is potentially unwanted or malicious activity Continuous and rapid blinking of the hard drive activity LED when the server is not knowingly processing tasks can indicate background activity that may be unauthorized or malicious.
Option A is incorrect because while maintenance tasks could cause activity, they are usually known and scheduled, hence not unexpected.
Option B is incorrect because nearing maximum capacity affects performance but doesn't cause continuous, rapid LED blinking.
Option D is incorrect because while possible, a malfunctioning LED is less likely compared to the presence of background processes.