You Have Three Strains of Mice

Multiple Choice

You have three strains of mice:
A,B,and C.You experimentally manipulate each strain and find that all three show increased secretion of molecule X.Now you perform a parabiosis experiment with the three combinations of these mice:
AB,AC,and BC.You perform the same experimental manipulation as above on one mouse of each pair without directly affecting the other mouse and look for effects on the other mouse.You find no detectable effect on the unmanipulated partner in any of the combinations.What is the logical conclusion based on these results?

A) The effect on molecule X is not mediated by hormones.
B) The effect on molecule X is not mediated by nerves.
C) The effect on molecule X was just an artifact of the first experiment.
D) The effect on molecule X is controlled by higher integrative centers of the brain.