Cell wall is only absent in:

Explanation

Mycoplasmas are unique among prokaryotes due to their lack of a cell wall, which gives them flexibility and resistance to certain antibiotics. In contrast, Archaeobacteria have cell walls composed of unique substances, Eubacteria have peptidoglycan-based cell walls, and Cyanobacteria also have peptidoglycan in their cell walls, which supports their structure and function. Understanding these differences highlights the distinct characteristics of Mycoplasma within the prokaryotic kingdom.