|Question 11Verbal

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Geneticist Elaine Ostrander led an international collaboration in which Norbert Benecke and other researchers investigated the evolutionary history of size variation in modern dogs. The researchers identified multiple versions of the gene regulating the production of IGF-1 (insulin-like growth factor 1) in dogs and found that dogs of the same breed consistently share the same version of the gene. In a discussion of the study, a student hypothesizes that small breeds of dogs (for example, Havaneses) must share a version that represses IGF-1 production that would otherwise confer larger body size.
Which finding, if true, would most directly weaken the student's claim?
The majority of the most prevalent dog breeds have limited activity in the gene that regulates IGF-1 production.
A
The degree of size variation among dogs is greater than that of any other land-based mammal.
B
Some breeds with small body sizes and low IGF-1 concentrations have a different version of the gene regulating IGF-1 production than do Havaneses.
C
The gene that regulates IGF-1 production is not the only gene that influences body size in dogs but is the only such gene that shows within-breed version consistency.
D