A 38-year-old G6P4 is brought to the hospital by ambulance for vaginal bleeding at 34 weeks. She undergoes an emergency cesarean delivery for fetal bradycardia under general anesthesia. In the recovery room 4 hours after her surgery, the patient develops respiratory distress and tachycardia. Lung examination reveals rhonchi and rales in the right lower lobe. Oxygen therapy is initiated and chest x-ray is ordered. Which of the following is most likely to have contributed to her condition?

a. Fasting during labor

b. Antacid medications prior to anesthesia

c. Endotracheal intubation

d. Extubation with the patient in the lateral recumbent position with her head lowered

e. Extubation with the patient in the semierect position (semi-Fowler position)