The algae dies out in the zone of

ANS:A - degradation

The algae typically dies out in the zone of degradation. In the zone of degradation, organic matter is broken down by microorganisms through processes like decomposition and digestion. This breakdown consumes oxygen, which can lead to oxygen depletion in the water. As a result, algae and other aerobic organisms may die due to the lack of oxygen in the water. Therefore, the correct option is: a. degradation