<prompt> A one-year-old boy presented with hepatosplenomegaly and delayed milestones. The liver biopsy and bone marrow biopsy revealed presence of histiocytes with PAS positive cytoplasm. Electron microscopic examination of these histiocytes is most likely to reveal the presence of:Birbeck granules in the cytoplasmMyelin figures in the cytoplasmParallel rays of tubular structures in lysosomesElectron dense deposit in the mitochondria  <response>: Given scenario suggests Gaucher disease, in which glucocerebroside in lysosomes seen. Birbeck granules in the cytoplasm- seen in histiocytosis X 