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 liquid component of hybrid ionomer cements usually contains a water solution of: 
Select and explain. 
A. HEMA, B. Polyacrylic acid, C. Polyacrylic acid modified with methacrylate, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: The liquid component of hybrid ionomer cements usually contains a water solution of polyacrylic acid, HEMA, and polyacrylic acid modified with methacrylate. 
The powder component contains fluoroaluminosilicate glass particles of a conventional GIC plus initiators, such as camphorquinone, for light curing and/or chemical curing. The acid-base reaction begins upon mixing and continues after polymerization at a much slower rate than for conventional GICs, because less water is present and the reaction is much slower in the solid phase than in the liquid phase.
Ref: Phillip’s Science of Dental Materials ed 12 pg 326