Step 1: Understanding Aspergillosis.
Aspergillosis is a fungal infection caused by the Aspergillus species. It commonly affects poultry and other animals, especially in confined or poorly ventilated environments.
Step 2: Analyzing the options.
(A) fungal: Correct — Aspergillosis is a fungal disease caused by the Aspergillus species.
(B) bacterial: Incorrect — Aspergillosis is not caused by bacteria.
(C) protozoan: Incorrect — Protozoan infections are caused by protozoa, not fungi.
(D) viral: Incorrect — Aspergillosis is a fungal disease, not viral.
Step 3: Conclusion.
The correct answer is (A) fungal, as Aspergillosis is caused by fungi.