The most likely cause of the failure in communication between the professor and Zereth is d. Noise.
Noise refers to anything that might cause us not to communicate a message effectively to our intended recipient.
The bad cold that Zereth has is noise because it is preventing the professor and Zereth from being able to communicate in a manner that will allow for information to be passed effectively.
Find out more on the communication process at https://brainly.com/question/1083194.