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 main advantage of composites over unfilled direct filling resin is their: 
Select and explain. 
A. Higher solubility in saliva, B. Lower modulus of elasticity, C. Esthetic excellence, D. Lower thermal co-efficient of expansion
D: Lower thermal co-efficient of expansion
Answer: D: Lower thermal co-efficient of expansion 
Explanation: None