Which one of the following describes a covert timing channel?
A. Modulated to carry an unintended information signal that can only be detected by special, sensitive receivers.
B. Used by a supervisor to monitor the productivity of a user without their knowledge.
C. Provides the timing trigger to activate a malicious program disguised as a legitimate function.
D. Allows one process to signal information to another by modulating its own use of system resources.
