Answer :
Answer:
Gross primary production - autotrophic respiration.
Explanation:
Primary production may be defined as the process of formation of organic compound from the photosynthesis. The plants are known as producers in the ecosystem.
More than 90% of the energy is lost from the one trophic level to the next trophic level. The net primary productivity can be calculated by the groos primary productivity produced by the plant minus the productivity lost during the process of respiration of plants.
Thus, the correct answer is option (4)