Which choice most logically completes the text?

Source Texts

Text

Evan MacLean and colleagues evaluated behavioral and genetic data from over 14,000 dogs, representing more than 100 breeds, and found that genetic variations track to differing extents with behavioral variations between the breeds. This was the case for the behavioral categories of dog rivalry and excitability but was especially pronounced for attachment and attention-seeking, which can be seen when a dog solicits affection or attention. In another study, researchers found that the boxer and the Yorkshire terrier breeds exhibit very different levels of attachment and attention-seeking. When considered in light of the study by MacLean and colleagues, this finding suggests that

boxers and Yorkshire terriers are more likely to share genes associated with attachment and attention-seeking than to share genes associated with dog rivalry or excitability.

there may be a greater tendency toward attachment and attention-seeking in boxers and Yorkshire terriers than in some other dog breeds.

there may be a substantial dissimilarity between boxers and Yorkshire terriers in the genes associated with attachment and attention-seeking.

individual boxers may display higher levels of attachment and attention-seeking than individual Yorkshire terriers do.