An alloy steel chain sling must be removed from service if there is evidence that ____________.

An alloy steel chain sling must be removed from service if there is evidence of replacement links having been used to repair the chain because using replacement links can compromise the sling's overall integrity and strength. Each component of a chain sling is engineered to work together, and replacing a link with a component that is not identical in material, grade, or strength can introduce weaknesses. This can lead to potential failures during lifting operations, which poses significant safety risks.

Regarding the other options, although they indicate wear or alterations to the sling, they might not always necessitate removal from service. For instance, a painted chain might reflect past maintenance efforts, rust can often be cleaned off and assessed for usability, and a worn label may simply require making the necessary identification visible again rather than a complete removal from service. Only the use of non-matching replacement links definitively signals a significant alteration that can affect safety, thus justifying removal from use.