Microorganisms developed from more complex organisms?

Oxygen played a key role in the evolution of complex organisms, according to new research published in BMC Evolutionary Biology. The study shows that organisms containing more varied cell types evolved following increases in atmospheric oxygen.

Hope it helps uh.

the answer to your question is b

common management practices in dairy and poultry farming are: (i) proper shelter facilities and their regular cleaning. (ii) some basic hygienic conditions such as clean water, nutritious food, etc. (iii) animals are kept in spacious, airy, and ventilated place.