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
An elderly diabetic has left sided orbital cellulites, CT scan of paranasal sinuses shows evidence of left maxillay sinusitis. Gram stained smear of the orbital exudates shows irregularly branching septate hyphae. The following is the most likely aetiological agent - 
Select and explain. 
A. Aspergillus, B. Rhizopus, C. Mucor, D. Candida
A: Aspergillus
Answer: A: Aspergillus 
Explanation: None