Why might turbidity be a misleading metric for water quality?

Turbidity is a measurement of the cloudiness or haziness of water, primarily caused by suspended solids, such as silt, clay, and organic matter. The correct choice identifies a key limitation of turbidity as a water quality metric: it does not provide information on the number or size of the particles that contribute to the turbidity. While it captures the overall clarity of the water, turbidity does not discern whether the suspended materials are harmful bacteria, larger particles, or benign substances. This is significant because different particles can have different implications for water quality and safety. Therefore, while turbidity can indicate that something is present in the water, it does not help determine whether that presence is problematic or what specific types of contaminants might be involved.

The other choices touch on different aspects of water quality measurement but do not accurately communicate why turbidity is misleading. For instance, turbidity is not related to temperature variations or exclusively indicative of large particles, and it does not directly measure chemical contaminants. Hence, while turbidity can be a useful parameter, relying solely on it could lead to misunderstandings about the true quality and safety of the water.