You are taking care of a farmer who professes to be a lay herbalist. She wildcrafts for feverfew which she uses to treat her headaches. You query her as to how often she is taking feverfew. She says may be once a month or so. Had she reported that she was taking feverfew on a routine basis which of the following labs would you want to order?
A. A PT/INR
B. Blood Glucose
C. A WBC
D. A BUN