Which one of the following agents is most useful in the maintenance of sinus rhythm in patients with atrial fibrillation.. Amiodarone

Which one of the following agents is most useful in the maintenance of sinus rhythm in patients with atrial fibrillation?
A.A Verapamil
B.A Diltiazem
C.A Ibutilide
D.A Amiodarone***
E.A Digoxin.