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: ENT
All of the following statements about sodium fluoride in otosclerosis are true, except - 
Select and explain. 
A. Acts by inhibiting proteolytic enzymes in cochlea, B. Acts by inhibiting osteoblastic activity, C. Is contraindicated in chronic nephritis, D. is indicated in patients with a positive schwartze sign
B: Acts by inhibiting osteoblastic activity
Answer: B: Acts by inhibiting osteoblastic activity 
Explanation: None