Answer:
B. use a familiar concept to communicate an idea
Step-by-step explanation:
Basically, Passage 2 states the hypothesis that spotted green pigeon is a descendant of an island hopping bird and throughot the article, it provides evidence for this statement.
The discovery is that, since the DNA found in a green pigeon's feather was fragmented and they had to analyze only parts of it, the bird had an unique sets of DNA which distinguish it from other members of the pigeon species.
These analyzed parts of DNA are refered to as "mini barcodes".
Since target audience for this article might not be fully familiar with the concept and functions od DNA, researchers used a more familiar concept of barcodes as an analogy to communicate their idea and explain their discovery.