While a single grade, like a C-, may not solely determine your admission to an Ivy League school, these institutions typically look for strong academic performance. It's crucial to strive for excellence in your coursework and balance any lower grades with outstanding achievements in other areas, such as extracurricular activities, standardized test scores, and personal accomplishments. Admission decisions consider the overall profile of an applicant, so focus on showcasing your strengths and addressing any weaknesses in your application.