This question is asking what left dominant circulation means. I suppose it wants us to infer that the PDA is supplying the diaphragm surface and AV node.
It is confusing to me because normally the Right marginal artery supplies the diaphragmatic border (acute margin) of the heart. I'm not sure that it changes in left dominant circulation. Furthermore it would not branch off the PDA, although maybe parts of it are supplied by the PDA
Also the AV node is supplied by the Atrioventricular nodal artery, which can be a branch off of the LCA or the LCX
but not really the PDA
so confusing question for me but the point is to know the course of left dominant circulation to the PDA