This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hepatitis, Subject name: Medicine
Most common viral cause of Fulminant hepatic failure in pregnancy? 
Select and explain. 
A. HAV, B. HBV, C. HCV, D. HEV
D: HEV
Answer: D: HEV 
Explanation: HEV- increases risk of fulminant hepatic failure in pregnancy