Answer: Option A
Explanation:
Primary productivity can be defined as the phenomenon in which the plants make food by the help of process photosynthesis and plants itself use the carbohydrates produced by them.
The oxygen that is produced as a by product from the plants is more than it is consumed by the animals.
There is a gain in the organic carbon by the organism as the amount of organic matter increases as we go up.
Hence, the correct answer is option A
