On an ABG, pH of 7.2, pO2 of 46, pCO2 of 80 are indicative of:

ABG shows severe hypoxia with hypercarbia with acidosis suggestive of type 2 respiratory failure. ARDS and acute asthma both have Type 1 Respiratory Failure and are ruled out. So we have to select between options A and C. Interstitial Pneumonitis on routine presentation will not have such low oxygen values but an acute exacerbation of chronic bronchitis will definitely present with low oxygen values.