69 yo M evaluated in the ED for a 1 week history of progressive exertional dyspnea followed by the development of rest dyspnea. He reports an unchanged nonproductive cough with chest pain. Been sleeping in a reclining chair at night.What is the most likely diagnosis for this patient based on the given symptoms? [Medicine]
a) Atrial fibrillation
b) Pneumothorax
c) Heart failure
d) Pulmonary embolism