Final answer:
The true statement about energy in ecosystems is related to the '10% rule', where only about 10% of the energy is passed on to the next higher trophic level, and the rest is lost or used by the organisms at that level.
Step-by-step explanation:
True Statement about Energy in Ecosystems
In ecosystems, energy transfer between trophic levels is inefficient, with much of the energy lost at each transfer. Statement A is incorrect because consumers typically pass on only about 10% of the energy they get from a lower trophic level, not 20%. Statement B is also incorrect, as it's not specifically urine and feces where the majority of energy is lost in primary consumers; it includes a combination of life processes like metabolism. Statement C suggests 10% of energy is lost as heat which is partially true, but it's a misleading statement as a much larger percentage is lost (around 90% is used or lost at each level, much of it as metabolic heat). Statement D is incorrect, as primary producers do not excrete urine and feces; energy they absorb is used for their growth, maintenance, and respiration with a large portion lost as heat.
The only truly accurate concept here, with regards to the transfer of energy between levels is the 10% rule, which states that only about 10% of the energy at one trophic level is passed on to the next higher trophic level; the rest is used by the organisms or lost to the environment primarily as heat due to metabolic processes.