The correct answer is: B. Both (i) and (ii)
The coliform test is a series of tests used to determine the presence of coliform bacteria in water. Coliform bacteria are a group of bacteria that are found in the intestines of warm-blooded animals. They are not harmful in themselves, but their presence in water indicates that the water may be contaminated with fecal matter.
The coliform test consists of three steps: the presumptive coliform test, the confirmed coliform test, and the completed coliform test.
The presumptive coliform test is a simple test that detects the presence of coliform bacteria. It is done by adding a sample of water to a culture medium that contains a substance that coliform bacteria can use to grow. If coliform bacteria are present in the water, they will grow on the culture medium and produce a visible colony.
The confirmed coliform test is a more specific test that confirms the presence of coliform bacteria. It is done by transferring a sample of the growth from the presumptive coliform test to a different culture medium that contains a substance that only coliform bacteria can use to grow. If coliform bacteria are present in the water, they will grow on the culture medium and produce a visible colony.
The completed coliform test is a test that determines the number of coliform bacteria in a sample of water. It is done by transferring a sample of the growth from the confirmed coliform test to a third culture medium that contains a substance that coliform bacteria can use to grow. The number of colonies that grow on the culture medium is then counted.
The coliform test is a valuable tool for determining the safety of water. It is used to monitor water supplies for coliform bacteria, and it is also used to test the effectiveness of water treatment processes.