A nurse in the emergency department is caring for a client who has pulmonary edema, reports dyspnea, and appears anxious. The client's blood pressure is 108/79 and his apical pulse is 112. Which of the following interventions is the nurse's priority?
a. Administer high-flow oxygen at 5 L/min by facemask to the client
b. Place the client in high-Fowler's position with legs dependent
c. Give the client sublingual nitroglycerin
d. Reassure the client
