An 18-year-old woman has eaten homemade preserves. Eighteen hours later, she develops diplopia, dysarthria, and dysphagia. She presents to the emergency room for assessment and on examination her blood pressure is 112/74 mmHg, heart rate 110/min, and respirations 20/min. The pertinent findings are abnormal extraocular movements due to cranial nerve palsies, difficulty swallowing and a change in her voice. The strength in her arms is 4/5 and 5/5 in her legs, and the reflexes are normal. Which of the following is the most likely causative organism?