A client is brought to the emergency department by ambulance after being involved in a motor vehicle accident. The nurse finds that he has decreased breath sounds over the left lung fields. What might the nurse suspect is the cause?

A. Asthma exacerbation typically causes wheezing or bronchospasm and would not usually cause decreased breath sounds in one lung. B. Pulmonary embolism may cause breathlessness or decreased oxygen levels, but it wouldn't typically cause unilateral decreased breath sounds. C. Pneumothorax is the most likely cause, as air in the pleural space can collapse the lung, leading to decreased or absent breath sounds on the affected side. D. Pulmonary edema typically causes bilateral crackles and would not cause unilateral decreased breath sounds.