The energy pyramid below shows a possible amount of energy, in kilocalories, available in the organisms at each trophic level in an ecosystem.

According to the law of conservation of energy, energy can neither be created nor destroyed. If this is true, why is there less energy in the top of the energy pyramid than there is in the bottom of the energy pyramid?
A.
Organisms in the top of the energy pyramid use up energy the fastest.
B.
The law of conservation of energy does not apply to ecosystems.
C.
The extra energy in the bottom is slower to reach the top.
D.
Energy is lost between each trophic level as heat.

D. Energy is lost between each trophic level as heat.