Answer:
D Species
Step-by-step explanation:
Living organisms have been organized into groups using the Kingdom to Species classification. Kingdom level represents the least specific while Species level represents the most specific. Prior to the discovery of DNA, classification of organisms has been based on structural similarities i.e. organisms that look similar are classified into the same species.
However, the discovery of DNA, put a stop to the erroneous classification of organisms based on structural similarities as there were many exceptions to this. Since members of the same species have a nearly identical DNA, it is used to divide its organisms based on DNA sequences
instead of structural similarities.