What is the measure of particulate matter that is suspended in water known as?

Answer: B — Turbidity

The measure of particulate matter that is suspended in water is known as turbidity. Turbidity refers to the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye. These particles can include sediment, algae, and other contaminants that can affect the quality of the water. Monitoring turbidity is crucial because it provides insights into water quality and safety. High turbidity levels can indicate the presence of harmful substances and can impair the ability of disinfectants to effectively treat the water. Additionally, it can impact aquatic life by blocking sunlight and affecting photosynthesis. The other options, while related to water quality, do not specifically denote the measurement of suspended particles. For instance, contamination level and clarity are broader terms that do not focus solely on particulate matter, and filtration ratio refers to the effectiveness of a filtration process rather than a direct measurement of suspended particles in the water. Thus, turbidity is the most precise term for this phenomenon.