Which of the following measurements indicates water quality in terms of visibility?

The measurement that indicates water quality in terms of visibility is 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, and it affects the transmission of light through the water. High turbidity can result from a variety of factors, including sediment, microorganisms, or pollutants, and can reduce sunlight penetration, impacting aquatic ecosystems and water treatment processes.

In contrast, pH measures the acidity or basicity of water, indicating the concentration of hydrogen ions without providing information about visibility. Hardness relates to the concentration of calcium and magnesium ions, affecting the taste and scaling properties of water but not its clarity. Total dissolved solids (TDS) quantifies all dissolved substances in water but does not specifically measure visibility. Thus, turbidity is the most relevant measurement when assessing water quality with respect to visibility.