Young and Colleagues Studied the Genetic Mechanisms Underlying the Differences

Young and colleagues studied the genetic mechanisms underlying the differences in social behavior in monogamous prairie voles and polygynous montane voles. Which constitutes a hypothesis?

A) They asked whether vasopressin, which stimulates V1a receptors in the brains of prairie voles, is responsible for activating the male reward system, causing them to maintain pair bonds.
B) They suggested that male prairie voles would have more V1a receptors in their brains than male montane voles.
C) They knew that the V1a receptor protein, crucial to the vasopressin-based system of pair bonding, is encoded by the avpr1a gene.
D) They found that differences in vasopressin receptor expression and reproductive behavior was directly related to the length of microsatellite repeats in the promoter of avpr1a.