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
Ratio of polymer to monomer in cold cure resin 
Select and explain. 
A. 3:1 by volume and 2:1 by weight, B. 3:1 by weight and 2:1 by volume, C. 2:1 by volume and 2:1 by weight, D. 3:1 by volume and 3:1 by weight
A: 3:1 by volume and 2:1 by weight
Answer: A: 3:1 by volume and 2:1 by weight 
Explanation: When the powder and liquid components are mixed in the proper proportions, a doughlike mass results. Commercial products generally use a polymer-to-monomer ratio of approximately 3:1 by volume.