<prompt> A structure marked with a red arrow is derived from which of the following ?Bulbous venosusSeptum primumEndocardial cushionLeft venous valve  <response>: A structure marked with a red arrow is derived from endocardial cushion Structures derived from endocardial cushion are : Atrial septum Membranous pa of ventricular septum Atrioventricular canal, valves Aoo-pulmonary channels Any endocardial cushion defect Cardiac malformation 