A water body with lots of organic waste and lower dissolved oxygen is described as having?

• A. High BOD
• B. Low BOD
• C. High salinity
• D. High turbidity

Answer: (A)

Biological Oxygen Demand (BOD) is the amount of oxygen that microorganisms need to break down organic matter in water. When a water body contains a lot of biodegradable organic waste, microbes multiply and consume a large amount of dissolved oxygen as they decompose that material. This rapid oxygen use lowers the available dissolved oxygen for other aquatic life, so the water is described as having a high BOD and often appears oxygen-poor.

The other options don’t fit as closely. Salinity measures salt content, which isn’t a direct indicator of organic pollution or oxygen demand. Turbidity refers to cloudiness from suspended particles; while it can influence oxygen dynamics indirectly (for example by affecting light for photosynthesis or increasing settling oxygen demand), it doesn’t specifically describe the high consumption of oxygen by decomposing organic matter.