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': 'Pitting of direct filling gold usually results from \nSelect and explain. \nA. Using contaminated gold foil, B. Poor finished preparation, C. Improper stepping of condenser point, D. using small condenser point', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]