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
Occult hepatitis B is: 
Select and explain. 
A. HBV DNA < 104 copies/ml with HBsAg negative, B. HBV DNA < 104 copies/ml with HBsAg positive, C. HBV DNA < 104 copies/ml with HBeAg negative, D. HBV DNA < 104 copies/ml with HBeAg positive
A: HBV DNA < 104 copies/ml with HBsAg negative
Answer: A: HBV DNA < 104 copies/ml with HBsAg negative 
Explanation: Occult hepatitis B is defined by the presence of HBV DNA in serum or liver in the absence of HBsAg. Serum HBV level is usually less than 104 copies/ml. Occult HBV infection has been found in patients with HCC, past HBV infection, or chronic hepatitis C, and individuals without HBV serological markers.