Correct answer = D.
<p>  While 20% of patients with PE will have
     a Po2 > 80, virtually all will have a widened A-a gradient and
     respiratory alkalosis.  Similarly echocardiographic findings
     such as 'd RVEDD, 'd LVEDD, and paradoxical septal motion
     are found in >80% of patients with acute PE.  Sinus
     tachycardia is also nearly universal while a S1Q3T3 pattern on
     ECG is seen only rarely.