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: Medicine
Which of the following is most appropriate cause of urinary stone formation? 
Select and explain. 
A. High urinary oxalate, B. Low urinary Mg, C. Low urinary sodium, D. High urinary chloride
A: High urinary oxalate
Answer: A: High urinary oxalate 
Explanation: None