Which of the following is NOT a branch of the right coronary artery?

The correct answer is that the left anterior descending artery (LAD) is not a branch of the right coronary artery. The right coronary artery primarily serves the right side of the heart and supplies blood to the right atrium, right ventricle, and the inferior part of the left ventricle via its branches.

The conus artery is considered a branch of the right coronary artery and supplies the right ventricle's outflow tract. The posterior descending artery (PDA) is also typically a branch of the right coronary artery, especially in a right dominant coronary system, and it supplies the inferior part of the heart. The acute marginal artery branches off the right coronary artery and provides blood to the right ventricle as well.

In contrast, the LAD arises from the left coronary artery and is responsible for supplying blood to the anterior and lateral parts of the left ventricle, as well as the interventricular septum. Hence, it is classified as a branch of the left coronary system and not the right.