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
According to ADA specification #1 for amalgam, what is the acceptable dimensional change? 
Select and explain. 
A. -20 to +20 micron/cm, B. -10 to +10 micron/cm, C. -20 to +10 micron/cm, D. -10 to +20 micron/cm
A: -20 to +20 micron/cm
Answer: A: -20 to +20 micron/cm 
Explanation: According to ADA specification #1 for amalgam, the acceptable dimensional change is -20 to +20 micron/cm.
Reference: Marzouk Operative dentistry, pg-108