The energy present in the ecosystem is being conveyed from producers to each level of the ecosystem. Photosynthesis is the process involve in the conversion of the energy from the sun to chemical energy. The number of trophic levels in an ecosystem is confines to 4-5 only. Only 10 % of energy is being conveyed from one level to the next. If this will be the case, each level will have a decrease of energy. If a sixth level will be present, there will be not enough energy to provide the species on such level.
Answer is Option 1 - Not enough energy is available to be transferred from the fifth trophic level to the sixth trophic level to support organisms.