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.