Question

modern dog breeds are largely the result of 160 years of owners crossbreeding certain dogs in order to select for particular physical appearances. owners often say that some breeds are also more likely than others to have particular personality traits—basset hounds are affectionate; boxers are easy to train—but kathleen morrill and colleagues found through a combination of owner surveys and dna sequencing of 2,000 dogs that while physical traits are predictably heritable among purebred dogs, behavior varies widely among dogs of the same breed. which choice best states the main idea of the text? dog breeds would not exist without many years of human intervention in dogs reproduction. research fails to confirm a commonly held belief about dog breeds and behavior. the dog breeds most popular among owners have often changed over the past 160 years. a study of dog breeds is notable for its usage of both opinion surveys and dna sequencing.

Explanation:

The text first mentions the common belief that dog breeds have specific personality traits. Then it presents a study (using owner surveys and DNA sequencing of 2000 dogs) which shows that while physical traits are heritable in purebred dogs, behavior varies widely among same - breed dogs. So the main idea is that research (the study by Kathleen Morrill and colleagues) fails to confirm the common belief (that breeds have specific personality traits).

• Option A: The text is not mainly about the existence of dog breeds due to human intervention in reproduction. The focus is on behavior and the common belief vs research.
• Option C: There is no mention in the text about the popularity of dog breeds changing over 160 years.
• Option D: While the study used opinion surveys and DNA sequencing, this is just a detail of the research method, not the main idea. The main idea is about the research's conclusion regarding the common belief about dog breeds and behavior.

Answer:

B. Research fails to confirm a commonly held belief about dog breeds and behavior.