Answer :
The amount of energy at each trophic level decreases as it moves through an ecosystem. As little as 10 percent of the energy at any trophic level is transferred to the next level; the rest is lost largely through metabolic processes as heat. If a grassland ecosystem has 10,000 kilocalories (kcal) of energy concentrated in vegetation, only about 1,000 kcal will be transferred to primary consumers, and very little (only 10 kcal) will make it to the tertiary level. Energy pyramids such as this help to explain the trophic structure of an ecosystem: the number of consumer trophic levels that can be supported is dependent on the size and energy richness of the producer level.
Answer: The correct answer is A) Energy decreases.
Trophic level is a hierarchical level within an ecosystem that comprises of organisms having same functions within a food chain and have same nutritional relationships with respect to the source of energy.
For instance, producers form the first trophic level and all producers synthesize their food through photosynthesis.
As per the 10% law of energy transfer, transfer of energy from one trophic level to the next ( like from producers to primary consumers) is 10% and the rest 90% of the energy is utilized in various metabolic processes and released as heat in the atmosphere.
Thus, energy decreases as we move through different trophic levels.
