<prompt> Not a component of tetralogy of fallot -Pulmonary stenosisVentricular septal defectOverriding aortaPatent ductus arteriosus  <response>: Ans. is d i.e., Patent ductus arteriosus Tetralogy of falloto TOF is the commonest cyanotic congenital heart disease.o It has four componentsi VSDii Pulmonic stenosisiii Overriding or dextroposed aortaiv Right ventricular hypertrophyo Pulmonic stenosis right ventricular outflow obstruction is mainly due to infundibular stenosis. Obstruction at pulmonary valve level valvular stenosis is very uncommon only 10.Pentology of fallot consists of components of TOF plus atrial septal defect 