Central dot sign is seen in -: (A) Caroli's disease, (B) Primary sclerosing cholangitis, (C) Polycystic liver disease, (D) Liver hamartoma
Answer is A. Central Dot sign on CT or USG is seen in:

Caroli's disease (most common cause); 
Prebiliary cysts; 
Obstructive jaundice; and 
Periportal lymphedema.