Which Possible Reasons Does the Nurse Identify That Contribute to the Patient's

Which possible reasons does the nurse identify that contribute to the patient's black stools?

A) Takes ferrous sulfate 325 mg PO BID.
B) Hemorrhoids are irritated and bleeding.
C) Bleeding from a perforated gastric ulcer.
D) Incomplete small bowel obstruction.
E) Development of a Clostridium difficile infection.