In the first lecture, we outlined one working definition of a drug--"Exogenous chemicals used to change one's biology, psychology or behavior". Now that you've had some experience using that working definition and learning about different kinds of drugs, can you think of a case where the definition doesn't work. Specifically, can you think of an example of a substance that meets the definition, but doesn't fit our intuition of what a drug is? Or is there a substance that fits our intuition of what a drug is, but doesn't fit the definition? Please provide your reasoning.

Please send me answer in type form.