1. o A 57-year-old man comes to the community free clinic because of fever, chills, sore throat, and swollen glands in his neck for the past three days. He is homeless, and has not received preventive healthcare in over 30 years. Temperature is 39.0°C (102.2°F), pulse rate is 102/min and regular, respirations are 20/min, and blood pressure is 146/94 mmHg. Physical examination shows a disheveled, somewhat toxic-appearing thin man. Examination of the oropharynx shows pharyngeal erythema and edema, and a thick, gray membrane overlying the soft palate, uvula, and tonsils. Anterior and submandibular cervical lymphadenopathy is also noted. Which of the following antibiotics is the treatment of choice for this patient's condition?