Final answer:
The illusion 'Watchin' the black board' refers to a reference to watching the blackboard. It highlights the importance of paying attention and focusing on the task at hand, rather than being distracted or misinterpreting information.
Step-by-step explanation:
The illusion 'Watchin' the black board' refers to c) A reference to watching the blackboard.
This illusion is a play on words, using the phrase 'watchin' the black board' instead of 'watching the blackboard'. It highlights the importance of paying attention and focusing on the task at hand, rather than being distracted or misinterpreting information.