Which definition among those given below best describes a covert channel?

A.
A server program using a port that is not well known.

B.
Making use of a protocol in a way it is not intended to be used.

C.
It is the multiplexing taking place on a communication link.

D.
It is one of the weak channels used by WEP which makes it insecure.

Explanation:
A covert channel is described as: “any communication channel that can be exploited
by a process to transfer information in a manner that violates the systems security policy.”
Essentially,it is a method of communication that is not part of an actual computer system
design,but can be used to transfer information to users or system processes that normally would
not be allowed access to the information.