1st clue is that its a restrictive lung disease via the FEV1/FVC ratio being increased.
Next, the DLCO is decreased (normal is 80 to 120%), meaning an issue with the alveolar-pulmonary capillary barrier (a diffuse lung process).
The CT has classic findings for idiopathic pulmonary fibrosis.
The clinical picture (non-productive cough, SOB with exertion, afebrile) are consistent with idiopathic pulmonary fibrosis.
Overall a very non ambiguous question.