There's a certainty in Biology, but also in Physics, that states and experimentally supports that the transference of energy always occurs with loss of energy, though the thermodinamic law that states that the energy and matter are neither destroyed nor created, instead, they get transformed or transferred. On biological systems, such as trophic levels, we know that very low energy is transfered between each level. We can say then that the correct answer is the B option: 10 % of the energy is transferred, while 90 % is lost.