Final answer:
The most significant factor that advanced nursing in the twenty-first century was the better education of nurses, attributed to increased higher education opportunities for women and enhanced recognition of nursing as a profession. The correct option is C.
Step-by-step explanation:
The factor that best advanced the practice of nursing in the twenty-first century was better education of nurses. This advancement is tied to several factors, including the increase in opportunities for higher education for women and the validation of nursing and medicine as professional and crucial fields.
Throughout the twentieth century, women in nursing gained recognition for their roles, especially during wartime. Colleges expanded, and more women than ever before were pursuing degrees in healthcare fields, which led to a more educated nursing workforce.
These educated nurses contributed to a revolution in healthcare that saw a rise in life expectancy due to advances in medicine, including the development of immunizations and an emphasis on hygiene and preventative care.