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: Unknown
Which of the following is the most common complication of heart failure? 
Select and explain. 
A. Hydrothorax, B. Pneumothorax, C. Pyothorax, D. Hemothorax
A: Hydrothorax
Answer: A: Hydrothorax 
Explanation: The elevation of hydrostatic pressure in congestive heart failure causes transudation of fluid into the pleural cavity and, therefore, hydrothorax.