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': 'A male 45 years old wants his missing teeth to be replaced. Intraoral examination reveals Kennedy class 4 edentulous  maxillary arch. Impression is made with alginate.\nThe setting time of the material is affected by all of the following except: \nSelect and explain. \nA. Tap water, B. Temperature of the water, C. Hot weather, D. Insufficient spatulation', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Clinicians, however, can safely influence the setting time by altering the temperature of the water. The higher the temperature, the shorter is the setting time. The temperature of the mixing water should be controlled\xa0 carefully\xa0 within\xa0 a\xa0 degree\xa0 or\xa0 two\xa0 of\xa0 a\xa0 standard temperature,\xa0 usually\xa0 20\xa0 °C,\xa0 so\xa0 that\xa0 a\xa0 constant\xa0 and\xa0 reliable setting time can be obtained. In hot weather, special precautions should be taken to provide cool water for mixing so that premature gelation does not occur. It may even be necessary to precool the mixing bowl and spatula, especially when small amounts of impression material are to be mixed.\xa0\nTap water naturally contains certain levels of metallic ions, primarily\xa0 calcium\xa0 and\xa0 magnesium.\xa0 It\xa0 has\xa0 been\xa0 shown\xa0 that compared with distilled water for mixing of alginate impression material, the use of tap water with a high hardness may accelerate the setting of the alginate. If one observes that the setting time has decreased in a new office or clinic location, the\xa0 effect\xa0 of\xa0 the\xa0 hardness\xa0 of\xa0 the\xa0 tap\xa0 water\xa0 on\xa0 setting\xa0 time should be considered as a possible cause.\nInsufficient spatulation\xa0 results\xa0 in\xa0 failure\xa0 of\xa0 the\xa0 ingredients\xa0 to\xa0 dissolve\xa0 sufficiently. This leads to decrease in strength of the mix.\nReference:\xa0 Phillips’ science of dental materials / Kenneth J. Anusavice, Chiayi Shen, H. Ralph Rawls.—12th ed. Page no 174', 'role': 'assistant'}]