Ans. is 'c' i.e., Aspergillus Diagnosis of Aspergillus infection: o Histologic examination of affected tissue reveals either infarction, with invasion of blood vessels by many fungal hvphae, or acute necrosis, with limited inflammation and hyphae. o Aspergillus hyphae are hyaline, narrow, and septate, with branching at 45deg: no yeast forms are present in infected tissue. o Hyphae can be seen in cytology or microscopy preparations, which therefore provide a rapid means of presumptive diagnosis.