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
[{'content': 'Bonding of composite resins to tooth structure is by: \nSelect and explain. \nA. Covalent bond, B. Ionic bond, C. Mechanical, D. Vanderval forces', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]