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
Acalculus cholecystitis caused by:a) DMb) TPNc) Leptospirosisd) Estrogen therapy 
Select and explain. 
A. abc, B. bc, C. acd, D. bcd
A: abc
Answer: A: abc 
Explanation: None