Which ONE of the following is least likely to result in a sustained rise in pulmonary artery pressure?

The answer is C. Lobar pneumonia is usually a short-term illness with resolution without chronic lung damage.

Congenital shunts, i.e., ASD (A) which are pre-tricuspid produce pulmonary hypertension in adolescence. Chronic bronchitis and emphysema (B) results in chronic hypoxia which stimulates muscularization of the pulmonary vascular tree. Pulmonary fibrosis (D) has a similar effect, but eventually there is fibrous obliteration of the vasculature. Pulmonary thromboembolic disease (E) of the recurrent type leads to a progressive increase in pulmonary vascular resistence.