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: Microbiology
Microscopic examination of a patient's sputum shows aseptate fungus. Which of the following is an aseptate fungus? 
Select and explain. 
A. Aspergillus, B. Candida, C. Nocardia, D. Rhizopus
D: Rhizopus
Answer: D: Rhizopus 
Explanation: In biopsy specimens, Rhizopus is seen microscopically as nonseptate hyphae with broad, irregular walls and branches that form more or less at right angles. Cultures show colonies with spores contained within a sporangium. These organisms are transmitted by airborne asexual spores and invade tissues of patients with reduced host defenses. Patients with diabetic ketoacidosis, burns, or leukemia are paicularly susceptible. Ref: Levinson W. (2012). Chapter 50. Oppounistic Mycoses. In W. Levinson (Ed), Review of Medical Microbiology & Immunology, 12e.