The Patient's Heart Rate Is 165 Beats Per Minute

The patient's heart rate is 165 beats per minute.The cardiac monitor shows a rapid rate with narrow QRS complexes.The P waves cannot be seen,but the rhythm is regular.The patient's blood pressure has dropped from 124/62 mm Hg to 78/30 mm Hg.The patient's skin is cold and diaphoretic,and the patient is complaining of nausea.The nurse prepares the patient for

A) administration of beta blockers.
B) administration of atropine.
C) transcutaneous pacemaker insertion.
D) emergent cardioversion.