A Patient with a History of Atrial Fibrillation Has Contacted $\mathrm{X}$

A patient with a history of atrial fibrillation has contacted the clinic saying that she has accidentally overdosed on her prescribed warfarin (Coumadin) . The nurse should recognize the possible need for what antidote?

A) IVIG
B) Factor $\mathrm{X}$
C) Vitamin $\mathrm{K}$
D) Factor VIII