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': 'Which of the following represents early effect of primary trauma from occlusion \nSelect and explain. \nA. Vertical pockets, B. Generalized alveolar bone loss, C. Undermining resorption, D. d)Haemorrhage and thrombosis of blood vessels in PD ligament', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]