This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
A 65-year-old man is being evaluated for possible right pneumonectomy for bronchogenic carcinoma. The value most suggestive of postuperative problems, is 
Select and explain. 
A. Carbon monoxide diffusion capacity (DLCO) 55 percent predicted, B. Forced expiratory volume in 1 second (FEV1) 2L (83 percent of total forced vital capacity), C. Maximal oxygen uptake (MVO2) 12 mLlkg/min, D. Pa CO2 50 torr
D: Pa CO2 50 torr
Answer: D: Pa CO2 50 torr 
Explanation: All of the listed tests are used in evaluating pulmonary function. Disturbing values include DLCO less than 50 percent predicted, FEV1 0.8l (60 percent of FVC), MV02 <10 mllkg/min, PaC02 > 46 torr, Pa02 < 70 torr