Why an energy pyramid in any ecosystem typically is limited to four or five levels only?

The reason an energy pyramid is limited to four to five is because as the pyramid gets smaller at the top more and more energy is lost.  Primary producers get 100% of the energy, Primary Consumers get 10% . Secondary 1% Tertiary .1% and Apex get .01% so after that point it has little to no energy and the Apex is the highest on the food chain. 

Confused on question what should we be answering