The correct answer is: D. Virus
Viruses are the smallest and simplest of all living organisms. They are not cells, but rather tiny particles that contain genetic material (DNA or RNA) surrounded by a protein coat. Viruses cannot reproduce on their own, but must infect a host cell in order to replicate. Once inside a host cell, the virus takes over the cell’s machinery and uses it to produce more viruses. These new viruses can then go on to infect other cells, causing disease.
Polio and chicken pox are both caused by viruses. Polio is a viral infection that affects the nervous system. It can cause paralysis, and in some cases, death. Chicken pox is a viral infection that causes a rash of blisters on the skin. It is usually a mild illness, but can be more serious in young children and people with weakened immune systems.
Bacteria are single-celled organisms that are much larger than viruses. They can reproduce on their own, and many of them can cause disease. However, not all bacteria are harmful. Some bacteria are beneficial, and are necessary for human health.
Protozoa are single-celled organisms that are larger than bacteria. They can be free-living or parasitic. Some protozoa can cause disease, such as malaria and giardiasis.
Algae are simple, plant-like organisms that can be found in both aquatic and terrestrial environments. Some algae can cause disease, such as red tide.
In conclusion, the correct answer to the question “Which of the following micro-organism causes diseases like polio and chicken pox?” is: D. Virus.