Final answer:
Blood in the fetal aorta is directed primarily towards the brain, as it is of high priority for oxygenation during fetal development. Therefore, the most highly oxygenated blood in the fetus flows to the brain, making B) Brain the correct answer.
Step-by-step explanation:
The question is about the pattern of fetal circulation and specifically where the most highly oxygenated blood flows within a fetus. The most oxygenated blood in the fetal circulation bypasses the lungs, which are nonfunctional prior to birth, via the foramen ovale and ductus arteriosus and is primarily directed towards the brain. The correct answer to the question is B) Brain.
In fetal circulation, blood from the placenta is oxygen-rich and flows through the umbilical vein, bypassing the liver through the ductus venosus, and entering the right atrium. Here, it mixes with oxygen-depleted blood but most freshly oxygenated blood flows through the foramen ovale into the left atrium, then into the left ventricle, and finally into the aorta. The top priority for the distribution of this highly oxygenated blood is the fetus's brain, supplied by the carotid arteries that branch off from the aorta.