Answer: Limitation of energy
Explanation:
The energy is very limited as soon as it reaches the higher tropic level. The energy is highest at the basic level which meas at the producers.
As we move up to the next tropic levels only 10 of the energy is transferred to another level.
So, as we move up the energy keeps on decreasing so there is only 4 or 5 tropic level. Loss of energy in the form of heat and less transfer to another level limits the number of trophic level.