A Polar (Hydrophilic) Molecule Has Crossed from the Circulation into Neural

A polar (hydrophilic) molecule has crossed from the circulation into neural tissue. What is the most likely explanation as to where this occurred?

A) the arachnoid barrier, where CSF drains into the venous return
B) the blood-CSF barrier composed of choroid epithelial cells
C) the blood-brain barrier composed of endothelial cells
D) the endothelial cells surrounding vasculature that supplies blood to the circumventricular organs
E) all of the above