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: Pathology
Focal diffuse gallbladder wall thickening with comet tail reverberation aifacts on USG is seen in the following condition: 
Select and explain. 
A. Adenomyomatosis of gallbladder, B. Ca gall bladder, C. Adenomatous polyps, D. Xanthogranuloma
A: Adenomyomatosis of gallbladder
Answer: A: Adenomyomatosis of gallbladder 
Explanation: Adenomyomatosis is a type of hyperplastic cholecystoses, characterized by a benign proliferation of gallbladder surface epithelium with glandlike formations, extramural sinuses, transverse strictures, and/or fundal nodule ("adenoma" or "adenomyoma") formation. The classic appearance is focal wall thickening in the gallbladder fundus. The presence of cystic spaces and echogenic foci with "comet tail" reverberation aifact is diagnostic of adenomyomatosis. Ref: Longo D.L., Fauci A.S., Kasper D.L., Hauser S.L., Jameson J.L., Loscalzo J. (2012). Chapter 311. Diseases of the Gallbladder and Bile Ducts. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison's Principles of Internal Medicine, 18e.