This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Medicine
Diffusion capacity of lung is increased by? 
Select and explain. 
A. CHF, B. Pulmonary embolism, C. Chronic lung disease, D. Anemia
A: CHF
Answer: A: CHF 
Explanation: DLCO increased in mild CHF,alveolar hemorrhage,polycythemia,left to right shunts.