The Nurse Is Caring for a Patient on a Gastrointestinal

The nurse is caring for a patient on a gastrointestinal unit. The nurse would be most concerned if a patient reported which of the following?

A) "My stool is soft and dark brown; I usually move my bowels twice a day."
B) "Lately, I've had two or three loose, sticky black stools every day."
C) "My stool has been dark green and hard to pass lately."
D) "Usually I move my bowels every day and the stool is light brown."