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: Surgery
Osteoporosis is caused by all except ? 
Select and explain. 
A. Fluorosis, B. Hypogonadism, C. Hypehyroidism, D. Hyperparathyroidism
A: Fluorosis
Answer: A: Fluorosis 
Explanation: Ans. is 'a' i.e., Fluorisis