Final answer:
Sedimentation in water purification leads to a decrease in the amount of organic matter as floc particles settle at the bottom of the tank, which can also remove some bacteria present in the water.
Step-by-step explanation:
Sedimentation as a method of water purification results in a decrease in the amount of organic matter. During the process of sedimentation, floc particles settle to the bottom of the sedimentation tank, allowing the clear water on top to flow through filtration units. This step in water treatment removes suspended solids, which largely consist of organic materials and can also trap some of the bacteria. Consequently, the bacteria count does not increase; it is reduced because the bacteria are included in the floc particles that settle out or are trapped and removed during subsequent filtration. The sedimentation process itself does not directly affect the amount of hydrogen, the flow rate of water, the destruction of vitamins, or an increase in the bacterial count. Therefore, the correct answer is b. A decrease in the amount of organic matter.