The total energy fixed by a green plant is called:

The correct answer is Option (2) → Primary Production

Note: The given answer is as per the official NTA Answer Key. However, the question can have more than one correct answer, i.e. both Option (2) and Option (4), as explained below. “Primary production” is the broad name for all the organic matter that green plants make in photosynthesis, and NTA takes it as the answer. “Gross” production is the more exact name for the same total, used to tell it apart from the net amount left after respiration.

Option (1) Net Production — Incorrect. Net production is what is left after respiration losses are taken away. It is the part available to herbivores and decomposers, not the total fixed.

Option (2) Primary Production — Correct. It is the production of the first trophic level, the green plants.

Option (3) Secondary Production — Incorrect. Secondary productivity is the rate of formation of new organic matter by consumers, not by green plants.

Option (4) Gross Production — Correct as well. It is the whole amount made before respiration is subtracted.

NCERT Extract:
Productivity – “A constant input of solar energy is the basic requirement for any ecosystem to function and sustain. Primary production is defined as the amount of biomass or organic matter produced per unit area over a time period by plants during photosynthesis. It is expressed in terms of weight (g m^–2) or energy (kcal m^–2). The rate of biomass production is called productivity. It is expressed in terms of gm^–2 yr ^–1 or (kcal m^–2) yr^–1 to compare the productivity of different ecosystems. It can be divided into gross primary productivity (GPP) and net primary productivity (NPP). Gross primary productivity of an ecosystem is the rate of production of organic matter during photosynthesis. A considerable amount of GPP is utilised by plants in respiration. Gross primary productivity minus respiration losses (R), is the net primary productivity (NPP).”