A 53-Year-Old Woman Arrives at the Hospital with Bleeding into the Back

A 53-year-old woman arrives at the hospital with bleeding into the back of the throat and has a coagulation screen performed.She has no history of abnormal bleeding before this despite major stress to hemostasis in the past: she was in a major automobile accident at age 37 and has had impacted wisdom teeth extracted.Her coagulation results follow:
$\begin{array}{|l|l|l|l|}\hline& \begin{array}{l}\text { Patient's } \\\text { Results }\\\\\end{array} & \begin{array}{l}\text { Reference } \\\text { Range}\\\\\end{array} & \begin{array}{l}\text { 1:1 Mix with } \\\text { Normal Plasma }\\\\\end{array} \\\hline \text { Prothrombin time (PT) } & \begin{array}{l}13.1 \\\text { seconds }\end{array} & \begin{array}{l}11-15 \\\text { seconds }\end{array} \\\hline \begin{array}{l}\text { Partial thromboplastin } \\\text { time (PTT) }\end{array} & \begin{array}{l}87 \\\text { seconds }\end{array} & \begin{array}{l}25-37 \\\text { seconds }\end{array} & \begin{array}{l}35\end{array}\\\hline \text { Fibrinogen } & 380 & 200-400 \\& \mathrm{mg} / \mathrm{dL} & \mathrm{mg} / \mathrm{dL} \\\hline\end{array}$
Which of the following is the most likely cause for her bleeding?

A) factor XII deficiency
B) factor IX deficiency
C) factor VIII deficiency
D) factor VIII inhibitor