<prompt> All the following statements about Emphysema are true exceptBreathlessness is the characteristic presenting symptomDiffusion rate of carbon monoxide is reducedRestrictive pattern on pulmonary function test is seenLong term bronchodilator therapy does not improve lung function  <response>: The hallmark of Emphysema is air flow obstruction and pulmonary function test show an obstructive patters Ref Harrison 19th edition pg 306e-4 