In which of the following conditions might you observe a buildup of pus?

Osteomyelitis is an infection of the bone that can be caused by bacteria or other pathogens. This infection can lead to the formation of pus, which is a thick fluid composed of white blood cells, dead tissue, and bacteria. The buildup of pus occurs as the body’s immune system responds to the infection. The affected bone and surrounding tissue often become inflamed and painful, and in severe cases, abscesses may form. This accumulation of pus can be seen in imaging studies, alongside signs of bony destruction.

Other conditions listed may involve inflammation or immune responses, but they typically do not result in the kind of pus buildup observed in osteomyelitis. Nephritis, for example, refers to inflammation of the kidneys and may involve some degree of immune response but does not typically produce pus in the same way. Psoriasis is primarily a skin condition characterized by rapid skin cell turnover and does not lead to pus formation. Multiple sclerosis is a neurological condition affecting the central nervous system with no association with pus accumulation. Thus, osteomyelitis stands out as the condition most likely to produce pus due to its infectious nature.