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
Polycythemia may be a features of all of the following except 
Select and explain. 
A. Gastric carcinoma, B. Hepatoma, C. Cushing's syndrome, D. Hypemephroma
A: Gastric carcinoma
Answer: A: Gastric carcinoma 
Explanation: None