Step-by-step explanation:
a. The causative organism for cholera is Vibrio cholerae, which is a gram-negative bacterium that produces a toxin causing severe diarrhea and dehydration.
b. Bilharzia, also known as schistosomiasis, is caused by parasitic flatworms of the genus Schistosoma. There are several species of Schistosoma that can cause the disease in humans, including S. haematobium, S. mansoni, and S. japonicum. These parasites are commonly found in freshwater snails and can infect humans through contact with contaminated water.
c. The causative organism for tuberculosis (TB) is a bacterium called Mycobacterium tuberculosis. TB is an infectious disease that primarily affects the lungs, but it can also affect other parts of the body, such as the kidneys, spine, and brain. TB is spread through the air when an infected person coughs or sneezes.