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
Proximal & distal renal tubular acidosis is differentiated by all except - 
Select and explain. 
A. Stones in kidney, B. Hypokalemia, C. Daily acid secretion, D. Presence of Fanconi syndrome
B: Hypokalemia
Answer: B: Hypokalemia 
Explanation: None