This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolic Disorders of Bone, Subject name: Orthopaedics
[{'content': 'Z score measures the bone mineral density compared to: \nSelect and explain. \nA. Age, race and sex matched individuals, B. Race and sex matched individuals, C. Sex matched individuals, D. None of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Z Score * Z score compares the patients BMD with that of adult of the same race, age and sex. Z Score indicates possible secondary osteoporosis. A Z Score of - 2 or below should trigger investigation for underlying disease.', 'role': 'assistant'}]