The correct option is D) Cows release all of their energy as heat.
Not all of the energy gets travelled from one trophic level to another. Observations have shown that only 10% of the energy travels from one trophic level to another when an organism of the upper trophic level consumes an organism of the lower trophic level. This is because most of the energy is lost by organisms as heat.
So, let's consider that there is 100% energy in plants that the cow eat. The cows will only receive 10% of the energy from the plants. The organisms that will eat the cows will only receive 1%of the energy.
The cow uses all but stores ten percent of what they eat.
For example, a plant produces 100 percent energy. The plant needs to use the energy for survival.
When a cow eats the plant, it only gains 10 percent of the energy.
Then, say a wolf eats the cow.
The wolf only gets 1 percent of the energy that is produced by the plant.