Which of the following is a fungus -
Klebsiella
Clostridia
Pneumocystis jerovecii
Listeria
Pneumocystis jerovecii is considered to be fungus based on following points:

It takes fungal stains like Gomori’s methanamine silver stain
It possesses chitin at all stages of development (component of fungal cell wall)
Based on molecular study of 5S –rRNA.