<prompt> Left border of heart on chest Xray is formed by -a Aortic archb Left Pulmonary arteryc Right atriumd Left ventriclee Right ventriclebcacad  <response>: Amongst the given options, left heart border is formed by Aortic knuckle formed by aortic arch and left ventricle.Some guides have included left pulmonary artery in the answer. But, it is pulmonary trunk which forms left heart border not left pulmonary artery. 