This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: mycology, Subject name: Microbiology
Pneumocystis carinii is a fungus because 
Select and explain. 
A. rRNA, mitochondrial protein gene sequence and presence of thymidylate synthase, B. Cell wall contains glucans, C. Angifungals are effective against P. Carini, D. Commonest infection in AIDS
A: rRNA, mitochondrial protein gene sequence and presence of thymidylate synthase
Answer: A: rRNA, mitochondrial protein gene sequence and presence of thymidylate synthase 
Explanation: Fugus - possess rigid cell wall containing chitin mannan and other polysaccharides. The cytoplasmic membrane containing sterols. Cytoplasm contains true nuclei with nuclear membrane, mitochondria and endoplasmic reticulum. Ref: Textbook of Microbiology, Ananthanarayan and Paniker; 9th edition