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': 'In plaster of paris, the setting time is primarily altered by: \nSelect and explain. \nA. Altering P/L ratio, B. Altering temperature of mixing water, C. Speed and length of hand spatulation, D. Addition of accelerators and retarders', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Chemical modifiers have been used extensively to increase or decrease the setting time of gypsum products; they are called retarders and accelerators\xa0respectively. The manufacturers use both types of compounds to formulate gypsum products with specific setting times.\nReference: PHILLIPS’ SCIENCE OF DENTAL MATERIALS, 12th ed page no 186', 'role': 'assistant'}]