Which of the following diseases has been eradicated worldwide, allowing vaccination to be discontinued?

The reason why smallpox is the correct answer lies in its unique history of global eradication. Smallpox was declared eradicated by the World Health Organization (WHO) in 1980 after a successful worldwide vaccination campaign. This campaign involved extensive vaccination in affected regions, and through concerted global efforts, the disease was completely eliminated. As a result, routine vaccination against smallpox was discontinued.

In contrast, the other diseases listed – mumps, tetanus, and polio – continue to be endemic in various parts of the world or have not been fully eradicated. Vaccination for these diseases remains essential to prevent outbreaks and protect public health. For example, mumps and tetanus still have reported cases, and polio remains endemic in some regions, highlighting the need for ongoing vaccination efforts for these diseases.