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': 'During mixed dentition stage, which of the following appliance should be used as a space maintainer for missing primary molars in mandibular arch: \nSelect and explain. \nA. Distal shoe, B. Nance holding arch, C. Passive lingual arch, D. Removable functional acrylic', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]