Answer:
The DNA under selection
Explanation:
In the given question, to understand the relationship between the evolutionary relationship among the Dogs the sequence of DNA has to be studied.
The sequence which has to be studied to study the relationship among Dog varieties will be the DNA which is under the selection. This could be accounted as that all the varieties of Dogs have been produced by the artificial selection that is a trait is chosen to produce hybrids. Choosing a trait means choosing a gene or a sequence of DNA that will face the selection pressure.
Since all the varieties of Dogs are the result of the artificial selection therefore they share a common ancestor and the under selection gene will be appropriate to study.