The correct option is D Pleuro pneumonia like organism
Mycoplasmas were discovered as the causative agents of a sheep and human diseases which is characterised by the accumulation of fluid in pleural cavities of lungs. The causative agents, as isolated and cultured from pleural fluid, were revealed as wall-less bacteria-like organisms. Owing to their resemblance to bacteria, they were names as PPLO, the pleuro-pneumonia like organisms. Thus, the correct answer is option D.