A 26yrs unmarried lady present with dyspnea. Her chest X-ray is normal, FVC is 92%, FEVI/FVC is 89% and DLCO is 59% of normal.On exercise her oxygen drops from 91% to 85%.Possible diagnosis is -

A 26yrs unmarried lady present with dyspnea. Her chest X-ray is normal

1.	A 26yrs unmarried lady present with dyspnea. Her chest X-ray is normal, FVC is 92%, FEVI/FVC is 89% and DLCO is 59% of normal.On exercise her oxygen drops from 91% to 85%.Possible diagnosis is -
A.	Primary pulmonary hypertension
B.	Alveolar hypoventilation
C.	Anxiety
D.	Interstitial lung disease
Answer» E.