Final answer:
The description that is NOT true about ventricular septal defect (VSD) is that it results when the bulbus cordis does not divide properly (option A ). The bulbus cordis's division is not directly related to VSD, which actually involves a defect in the interventricular septum causing blood to mix between the two ventricles.
Step-by-step explanation:
The statement regarding ventricular septal defect (VSD) that is NOT true is: A. It results when the bulbus cordis does not divide properly. The bulbus cordis is involved in the formation of the heart, but improper division of the bulbus cordis is not directly related to VSD. Instead, VSD involves an issue with the interventricular septum, as described in option C, where the superior part of the interventricular septum fails to form, allowing blood to mix between the left and right ventricles.
Option E describes the physiological consequence of this defect, where blood is shunted from left to right because of the greater strength and pressure in the left ventricle compared to the right ventricle. Additionally, VSD does occur in about 1 in 500 births and it does result in the mixing of blood between the two ventricles as stated in options B and D, respectively.