Answer: Option A
Step-by-step explanation:
The addition of iron to the ocean can result in increasing the productivity of the ocean. This will affect the life of the organism living in their.
The organism that lives in water respire and use oxygen for this process. Once the productivity of the ocean is increased there is a lack of oxygen in ocean.
The biological demand of the ocean will increase and the organism will be limited in the water as there will not be adequate amount of oxygen left for the organism to consume it because of the increased productivity.
hence, option A is the correct where the increased productivity will lead to increased oxygen demand and its rate will be depleted.