At a Research Conference, You Meet a Graduate Student Who

At a research conference, you meet a graduate student who studies the hormonal underpinnings of mating behavior in two species of squirrel. "It turns out the difference between my two squirrel species is similar to the difference between the prairie and the montane voles," he says. You nod knowingly, and reply...

A) "Oh, so the promiscuous species has a lot of vasopressin and oxytocin receptors in the nucleus accumbus, blocking pair bonding, and the monogamous species doesn't?"
B) "Oh, so the monogamous species has a lot of vasopressin and oxytocin receptors in the nucleus accumbus, promoting pair bonding, and the promiscuous species doesn't?"
C) "Oh, so the polyandrous species has a lot of serotonin and dopamine receptors in the nucleus accumbus, promoting pair bonding, and the promiscuous species doesn't?"
D) "Oh, so the monogamous species has a lot of serotonin and dopamine receptors in the nucleus accumbus, promoting pair bonding, and the promiscuous species doesn't?"