This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
All of the following conditions are likely to be associated
with melaena except: 
Select and explain. 
A. Car. of the stomach, B. Car. of the rectum, C. Chronic duodenal ulcer, D. Portal hypertension
B: Car. of the rectum
Answer: B: Car. of the rectum 
Explanation: None