An Oxygen Sag Curve Occurs When

Multiple Choice

An oxygen sag curve occurs when

A) Fish population numbers sag.
B) Heavy metals that have entered a stream bind oxygen molecules and remove them from the available oxygen supply.
C) The breakdown of biodegradable wastes by bacteria lowers the available oxygen in the water for organisms with high oxygen requirements.
D) Carbon dioxide values exceed dissolved oxygen values.
E) Oxygen content in the air around a particular body of water becomes slightly lower than normal