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': 'Purpose of liners and bases is/are: \nSelect and explain. \nA. Pulp protection from thermal and chemical agents, B. Pulp protection from mechanical and electrical agents, C. Pulp medication, D. All of the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Many restorative dental materials that provide excellent properties for the bulk of a dental restoration may not protect the dental pulp during setting or during cyclic thermal or mechanical stressing. Pulpal protection requires consideration of:\n\nChemical protection.\nElectrical protection.\nThermal protection.\nPulpal medication.\nMechanical protection.\xa0\n\nLiners and bases are materials placed between dentin (and sometimes pulp) and the restoration to provide pulpal protection or pulpal response.', 'role': 'assistant'}]