In most ecosystems, the original source of energy for the living things in the system is the sun.
That's like finding the meaning of life,it simply can't be proven
The correct option is PHYLUM.
Scientists arranged living organisms into groups on the basis of the traits which they share with one another. The lowest rank in the groups is the specie while the kingdom is the highest rank. The ranks are arranged as follow:
Specie < Genus < Family < Order < Class < phylum < Kingdom.
Thus, the phylum is a combination of many classes.
