Call of Duty

A budding resident is determined to become the best ever interventional cardiology specialist at the hospital to eventually earn his dream fellowship position in the heart of New York City. To this end, he downloads various shooter games to practice his digital skills and settles on Call of Duty. Train, he does, until he becomes the best-rated shooter in the city. Unfortunately, his devotion to Duty diminishes his actual catheterization skills. The fellowship is awarded instead to his rival, Dr. Doolittle, who was shown how to deploy a medicated stent to a coronary artery by his talking parrot; the very same bird took him to parrot-dise on his last vacation before taking the medical boards exam. In his last training session of his residency, Dr. Doolittle independently inserts five stents in a patient without a snag, except for the one deployed to the posterior interventricular artery. The posterior interventricular artery arises from which of the indicated vessels?

Posterior interventricular artery arises from which numbered vessel?