<prompt> True about third hea sound isAbsent in Chr. Constrictive pericarditisAbsent in aoic aneurysmAbsent in MSNormal physiologically in Athletes  <response>: Answer is C Absent in MS: Third hea sound S3 is commonly seen in association with ventricular dysfunction. Ventricular function is usually. normal with MS and hence S3 is usually not a feature of MS. Physiological S3 may be heard in athletes, while constrictive Pericarditis and ischaemic hea disease MI are established causes of pathological S3. 