Final answer:
The eradication of smallpox was primarily due to effective vaccines and global cooperation through organized vaccination campaigns. The World Health Organization played a pivotal role, and improved public health measures also supported these efforts.
Step-by-step explanation:
Reasons for the Eradication of Smallpox
The eradication of smallpox around the world was a monumental achievement in public health made possible by several key factors. One of the primary reasons was the development of an effective vaccine, which was derived from the cowpox virus and later improved for safety and ease of administration. Furthermore, a coordinated effort at a global level, spearheaded by organizations such as the World Health Organization (WHO), fostered international cooperation and facilitated mass vaccination campaigns. These efforts, backed by the commitment of governments and non-governmental organizations around the world, ultimately led to the eradication of smallpox, with the last known case occurring in 1977 and the WHO declaring the disease eradicated in 1980. Additionally, improved sanitation, nutrition, and public health measures supported the vaccination efforts, although the key factor in smallpox eradication was immunization.
The correct answer to the question is: a) Effective vaccines and global cooperation.