What has yet to happen to diseases such as smallpox?

The option stating that diseases such as smallpox "haven’t been stamped out" accurately conveys that while smallpox has been eradicated, the phrase emphasizes the notion of actively eliminating a disease from existence. Although smallpox itself has indeed been eradicated, the broader context of public health recognizes that many other diseases continue to persist and affect populations worldwide. The wording suggests an acknowledgment of the efforts required to eliminate diseases thoroughly, highlighting ongoing challenges in disease control and eradication efforts.

This choice maintains relevance, as it points to the concept that while some diseases may be under control or reduced, the phrase implies that there is more work to be done in the field of epidemiology and public health regarding other infectious diseases.