Correct answer to this question is option D
A microorganism is an organism that is microscopic; this means such organism cannot be seen with the naked eye. Microorganism includes bacteria, fungi, viruses, protists, and archaea.
Many organisms serve as a source of antibiotics, for example penicillum produced the first discovered antibiotics. Streptomyces sp. produces the aminoglycoside antibiotics.
Nonpathogenic microorganisms are often used in the production of fermented food such as – yoghurt, cheese, bread, and wine.
Many microorganisms feed upon dead organic materials and help decompose them.
However, not all microorganisms are harmful to the human body; in fact, there are many microorganisms in the human body that help in the normal functioning in the human body.