The correct option is
A Transverse groove
A groove on the outer surface of the heart marking the division between the atria and the ventricles. A groove surface surrounding the heart separating the atria from the ventricles. It includes the right coronary artery, the tiny pulmonary vein, the coronary sinus, and the left coronary artery's circumflex branch.
So, the correct answer is 'Transverse groove'