A measure of how clear water is.

• A. Turbidity
• B. Photic Zone
• C. Salinity
• D. pH

Answer: (A)

Turbidity is the measure of how clear water is. It directly quantifies how hazy or cloudy water appears by assessing how suspended particles scatter light. When a lot of sediment, algae, or organic matter are in the water, turbidity increases and light penetration decreases, making the water look less clear. This matters ecologically because clearer water allows more light to reach aquatic plants and influences food webs and habitat quality. The photic zone relates to the depth that light can reach for photosynthesis, but it’s a depth concept influenced by turbidity rather than a direct measure of clarity. Salinity and pH describe chemical properties (salt content and acidity) and don’t indicate how clear the water is.