Read the following passage and answer the question. 'Adaeze had always been the most diligent student in her class. She spent long hours poring over her textbooks, rarely leaving her desk until she had mastered every concept. Her teachers admired her tenacity, though some of her peers found her single-minded dedication somewhat intimidating. Despite the social distance this created, Adaeze remained resolute, convinced that her sacrifices would yield dividends in the future.' The word 'tenacity' as used in the passage most nearly means