An energy pyramid shows how energy flows through an ecosystem. An image is provided. Each level gets only about 10% of the energy from the previous level. If living systems follow the law of conservation of energy, where does the remaining 90% of the energy go?

A. A It is used by decomposers during decomposition.
B. B It is converted into heat and energy for life functions.
C. C It is converted to matter during digestion.
D. D It is used by organisms in the lower trophic level.