B

Beta-D-glucan is a major cell-wall polysaccharide of many fungi and is released into blood during invasive infection; it is therefore used to detect Candida, Aspergillus and Pneumocystis infections, but Mucorales have negligible β-D-glucan in their cell walls, so the assay is typically negative in mucormycosis cases [Theel, 2013, PMID 22945270; Son, 2017, PMID 29190812].