EVERYDAY SCIENCE

Detailed explanation-1: -The organs then formed organ systems and thus complex organisms were formed. This is the hierarchy seen in the evolution of animals. Thus the correct ans is Cells→Tissues →Organs →Organ system i.e. option B. Note: The hierarchy is also a major characteristic to study the different phyla of the animal kingdom.

Detailed explanation-2: -The major levels of organization in the body, from the simplest to the most complex are: atoms, molecules, organelles, cells, tissues, organs, organ systems, and the human organism.

Detailed explanation-3: -The current taxonomic system now has eight levels in its hierarchy, from lowest to highest, they are: species, genus, family, order, class, phylum, kingdom, domain.

Detailed explanation-4: -Higher levels of organization are built from lower levels. Therefore, molecules combine to form cells, cells combine to form tissues, tissues combine to form organs, organs combine to form organ systems, and organ systems combine to form organisms.

Detailed explanation-5: -Cells make up tissues, tissues make up organs, and organs make up organ systems.