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': 'Terminal third of retentive arm is placed in \nSelect and explain. \nA. Gingival third, B. Junction of gingival third and middle third, C. Middle third, D. Junction of middle and occlusal third', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]