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
ZOE is made eugenol free by 
Select and explain. 
A. Acetic Acid, B. Alginic Acid, C. Phosphoric Acid, D. Ortho-Ethoxy Acid
D: Ortho-Ethoxy Acid
Answer: D: Ortho-Ethoxy Acid 
Explanation: None