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
The particle size in Williams E-Z Gold: 
Select and explain. 
A. 15 mm, B. 10 mm, C. 12 mm, D. 20 mm
A: 15 mm
Answer: A: 15 mm 
Explanation: Powdered gold is made by a combination of chemical precipitation and atomization, with an average particle size of 15 mm. The atomized particles are mixed together in wax, cut into pieces, and wrapped in No.4 or No.3 foil.
Several sizes of these pellets are available. This product is marketed as Williams E-Z Gold (Ivoclar-Williams, Amherst, NY).
Reference: Sturdevant operative dentistry. 7th EDITION, Page No:e68