<prompt> Pulmonary embolism is best diagnosed byUSGX-ray chestVentilation Perfusion scanCT scan  <response>: No option is absolutely correct.The pulmonary angiography has traditionally been considered as the gold standard test for pulmonary embolism. But, now a days CT contrast MDCTA is the investigation of choice.Amongst the given options, lung VQ scan is the best option as it is the 2nd choice of the investigation after MDCTA. 