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: Ophthalmology
All the following intraocular foreign bodies produce suppurative reaction except 
Select and explain. 
A. Copper, B. Zinc, C. Nickel, D. Gold
D: Gold
Answer: D: Gold 
Explanation: No reaction of gold (inert).