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 an alkaline type of renal calculi? 
Select and explain. 
A. Calcium stone, B. Uric acid stone, C. Cystine stone, D. All of the above
A: Calcium stone
Answer: A: Calcium stone 
Explanation: Alkaline - Calcium stone
Acidic - Uric acid and cystine stones