Which one of the following causes Pectus carinatum?

(B) Childhood asthma > Roentgenographic finding of childhood asthma include atelectasis (local parenchymal collapse), postobstructive infiltrates & air trapping caused by unidirectional expiratory obstruction.> CT scanning may demonstrate the nature and the exact location of obstruction of the central bronchi.> MRI may be superior to CT for delineating the extent of the underlying disease in the hilum, but it is usually reserved for cases in which CT findings are equivocal.> Bronchoscopy is the definitive diagnostic study. Particularly if tumor or foreign body aspiration is suspected.> The finding of tubular breath sounds on physical examination or an air bronchogram on chest radiograph in an area of atelectasis rules out complete airway obstruction> Bronchoscopy is unlikely to be of therapeutic benefit in this situation.# Pectus carinatum> Pigeon chest is frequently caused by severe asthma during childhood> Other causes - rickets, idiopathic.