Ingested water-soluble drugs follow the same absorption pathway as sugars and amino acids. Choose the most direct pathway for a water-soluble antidepressant, from absorption at the GI tract mucosa until it reaches the brain:

a. Lymphatic system > hepatic portal vein > portal venule rightarrow sinusoid > central vein > hepatic vein > heart & lungs > arteries > brain
b. Lymphatic system > veins > heart & lungs > arteries > brain
c. Hepatic artery > portal arteriole > sinusoid > central vein > hepatic vein > heart & lungs > arteries > brain
d. Veins > heart & lungs > hepatic artery > portal arteriole > sinusoid central vein > hepatic vein > heart & lungs > brain
e. Hepatic portal vein > portal venule > sinusoid > central vein > hepatic vein > heart & lungs > arteries > brain

The correct answer is option e.

Explanation:

The water-soluble antidepressant after getting absorbed within the gastrointestinal tract's mucosa layer drains into the hepatic portal vein by the process of passive diffusion.  

The hepatic portal vein associates the venule of the gastrointestinal tract and spleen with the liver sinusoids. Thus, the drug flows within the central vein and moves via the hepatic veins into the heart's inferior vena cava, from here it passes onto the lungs where it gets oxygenated and moves towards the brain and perform its activity.  

try using substitution:

x + y - 6 = x - y. (i'm not giving you the exact answer). since 0 = x - y, then sub 0 in the equation with x - y. combine your like terms, and then use inverse operations, and you'll have your answer.

: -)