* A. Mycoplasmas are the smallest free-living micro-organisms.

* B. Mycoplasmas are resistant to cell wall active antibiotics.

* C. Mycoplasmas are common commensals of the respiratory and urogenital tracts.

* D. Mycoplasmas stain well with the Gram's stain.

* E. Mycoplasmas grow slowly on enriched media.

Correct Answer: D