This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
Metamerism invariably involves _____. 
Select and explain. 
A. A color difference between two objects under one or more illuminant(s), B. One object having a lower chroma than another, C. One object having a lower lightness than another, D. A significant color change of one object as it moves from one illuminant to another
A: A color difference between two objects under one or more illuminant(s)
Answer: A: A color difference between two objects under one or more illuminant(s) 
Explanation: Metamerism is the phenomenon where a color match under a lighting condition appears different under a different lighting condition.