Your 18-year-old patient complains of an extremely sore thro…

Your 18-year-old patient complains of an extremely sore throat and that it hurts to swallow. Her symptoms began 48 hours ago. She mentions that her roommate in the dorm is being treated for strep throat. She is on no medication, has no past medical issues, and has no allergies. Her rapid strep test is positive. Which antibiotic would be first-line treatment for this patient?