Which symptom most strongly suggests acute cardiogenic pulmonary edema?

Pink, frothy sputum combined with severe orthopnea is pathognomonic of acute cardiogenic pulmonary edema. In this condition, elevated left-sided filling pressures force fluid across the alveolar-capillary membrane into the alveoli. The foam is produced by air mixing with protein-rich, blood-tinged fluid, creating the characteristic pink froth. Orthopnea — breathlessness that worsens when lying flat — occurs because recumbency increases venous return to an already overloaded left ventricle, exacerbating pulmonary congestion. Together, these two findings point unmistakably to acute cardiogenic pulmonary edema. Hemoptysis after a long flight (option A) raises concern for pulmonary embolism, which can cause hemoptysis but is associated with pleuritic chest pain, tachycardia, and risk factors for deep vein thrombosis rather than frothy sputum. Sudden calf pain with swelling (option C) suggests deep vein thrombosis, a precursor to pulmonary embolism, but does not indicate pulmonary edema. Pleuritic chest pain with a normal chest X-ray (option D) is more consistent with early pulmonary embolism or pleuritis, not cardiogenic pulmonary edema, which typically produces bilateral infiltrates or a bat-wing pattern on imaging. Recognizing the pink frothy sputum and orthopnea combination guides immediate interventions such as oxygen, diuresis, and vasodilators.