I'm giving my most personal view/analysis on this and you might agree or disagree with it:
The Question:
Extrapolating from the doomed fate of neophobic rats to their human counterparts is diffi cult. “But it means that some thing as simple as a personality trait could have physiological 20_____,” Cavigelli says.
A causes
B disturbances
C factors
D consequences
In my opinion, consequence leads to something while disturbance is the result (of a malfunction) that has been caused,(by something). And since a disturbance could be the result of a consequence, consequence seem more fitting to use in this case. I also think consquence describes something more general, long-term and multifaceted while disturbance describes an exact negative malfunction.
Hence, the disturbance itself is the result of a psychological consequence, and the correct wording of the meaning should be D: "But it means that something as simple as a personality trait could have psychological consequences*."