Question

The Earth consists of a variety of different organisms. Despite their diversity, however, some similarities on the structural and metabolic levels may be seen. These similarities can be attributed to

Answer 1

It seems that you have missed the essential options to answer this question, but anyway, here is the answer. The Earth consists of a variety of different organisms. Despite their diversity, however, some similarities on the structural and metabolic levels may be seen. These similarities can be attributed to similarities among organisms in their proteins and nucleic acids. Hope this answer helps.

Answer 2

The right answer is it can be attributed to similarities among organisms in proteins and nucleic acids (especially in their coding regions in their genome).

Genomes consist of coding regions, which correspond to genes, and non-coding regions. The coding part is the one that gives the proteins that are involved in the structure and metabolism of the individuals. if two individuals have a similar protein-giving genome, then they will probably have the same structure and metabolism.