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 causes primary infection in 
Select and explain. 
A. Rats, B. Mice, C. Humans, D. Rabbits
A: Rats
Answer: A: Rats 
Explanation: There are two known species of Pneumocystis - Pneumocystis carinii, commonly found in rats and Pneumocystis jirovecii seen in humans. Ref: Textbook of Microbiology, Ananthanarayan and Paniker; 9th edition