Anurse 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