A 25-year-old male presents to an emergency department with suddenonset right-sided pleuritic chest pain and breathlessness. On examination, he has arterial blood saturation of 90% in air and is afebrile. An X- ray shows a lung edge visible in the right hemithorax, beyond which no lung markings are seen. Which of the following conditions has most likely occured in this patient?

• A. Rib fracture
• B. Pleurisy
• C. Pneumonia
• D. Pneumothorax
• E. Aerophagy