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
Which of the following is true about Pneumothorax? 
Select and explain. 
A. Decreased Chest Expansion, B. Increased Breath Sounds, C. Increased Vocal Resonance, D. Dull percussion note
A: Decreased Chest Expansion
Answer: A: Decreased Chest Expansion 
Explanation: Answer is A (Decreased Chest Expansion): Chest Expansion may be Normal or Decreased in Pneumothorax. Pneumothorax is associated with reduced breath sounds, reduced vocal resonance, hyper-resonant percussion note and tracheal detion/mediastinal shift to opposite side.