Q. A 68-year-old woman presents to the emergency department with fever, cough, and shortness of breath for the past three days. She has a history of stroke with residual dysphagia. She is a non-smoker and does not drink alcohol. Her vital signs are: temperature 101.3°F (38.5°C), blood pressure 130/75 mmHg, heart rate 105 beats/min, respiratory rate 22 breaths/min, and oxygen saturation of 92% on room air. Lung auscultation reveals crackles in a specific lung field. A chest X-ray is performed, which shows consolidation. The patient's presentation is most consistent with aspiration pneumonia. In patients who aspirate while upright, which lobe of the lung is most commonly affected?