Explanation:

- The passage discusses the failure of governments to eradicate child labor and ensure education for all children.

- Blank 4 requires a conjunction that connects two negative statements.

- Options:

- 1, but: Typically contrasts two opposite ideas; not suitable here.

- 2, nor: Used to add a negative statement to a preceding one; appropriate here.

- 3, neither: Often paired with "nor" and typically not used alone in this context.

- 4, either: Usually pairs with "or" to show alternatives, rather than adding negatives.

- The sentence means no government has eradicated child labor, nor ensured education.

- Option 2, "nor," fits perfectly as it adds to the negative statement.