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': 'Landmark which is immune to surface deposition and resorption: \nSelect and explain. \nA. Xi point and Eva point, B. Point A and Point B, C. Porion and Basion, D. Pogonion and Gnathion', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Arcial growth of mandible: \n\nProposed by Ricketts.\nThe advantage was that the arc of growth can be constructed for every individual depending on\xa0the length of the core of the mandible.\nIn order to locate the central core, which is immune to surface deposition and resorption, he introduced 2 landmarks -\xa0Xi point and Eva point on the mandibular ramus.\nXi Point: Represents geometric centre of ramus.\nEva point: In dried mandible, the stress lines run on the medial aspect parallel to the external oblique ridge and ascend up the ramus. The stress lines fork into two at a \xa0particular point that was named as Eva point.\n\nRef: Shreedhar Premkumar 1st edition P:199', 'role': 'assistant'}]