The correct answer is c-Ziehl Nelsen stain.

Direct smears of pleural and peritoneal fluid are routinely stained with various methods to identify microorganisms and cells present in the fluid. Eosin-nigrosin stain is used to visualize fungal elements, while Gram stain is used to identify bacterial species. Leishman stain is used to visualize cells such as leukocytes and erythrocytes.

Ziehl Nelsen stain, on the other hand, is a special stain used to detect acid-fast bacilli (AFB) such as Mycobacterium tuberculosis, the causative agent of tuberculosis. AFB are characterized by their ability to retain the stain even after being washed with acid, hence the term "acid-fast". This stain is commonly used in the diagnosis of tuberculosis and other mycobacterial infections.

Therefore, the correct answer is c-Ziehl Nelsen stain, as it is not routinely used for staining pleural and peritoneal fluid.

References:

1. Forbes, B. A., Sahm, D. F., & Weissfeld, A. S. (Eds.). (2007). Bailey & Scott's diagnostic microbiology (12th ed.). Mosby Elsevier.
2. Koneman, E. W., Allen, S. D., Janda, W. M., Schreckenberger, P. C., & Winn Jr, W. C. (Eds.). (2006). Color atlas and textbook of diagnostic microbiology (6th ed.). Lippincott Williams & Wilkins.