|Question 10Verbal

Source Texts

Text
In an international collaboration, Elaine Ostrander, Alan K. Outram, and other researchers probed the evolutionary history of size variation in modern dogs. Scientific consensus held that early dogs had large body mass and that a genetic driver of smaller size in some breeds (e.g., bulldogs) developed only within the last 20,000 years as a result of selective breeding for characteristics favored by humans. Ostrander et al. assert that this explanation is flawed, having discovered that a mutation responsible for variants of IGF1, a gene found in many mammals that regulates production of insulin-like growth factor 1, is ubiquitous in domestic dog breeds.
Which finding, if true, would most directly support the researchers' assertion?
The mutation related to IGF1 influences body size and is found in 3,000-year-old genetic material from fossils of Siberian wolves (Canis lupus campestris), an ancestor of dogs.
A
One variant of IGF1 is found only in smaller dog breeds like bulldogs and appears to have emerged no more than 20,000 years ago.
B
An additional mutation related to IGF1 affects the development of characteristics other than body size in smaller dog breeds like bulldogs.
C
IGF1 has been isolated in genetic material from fossils more than 20,000 years old of the red wolf (Canis rufus) and certain other species related to dogs.
D