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': 'Selective pressure impression technique indicated in \nSelect and explain. \nA. Firm healthy mucosa covering over the ridge, B. Flabby ridges, C. Knife edge with movable mucosa, D. When sharp bony spicules are present in the ridge', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]