Under which condition should cans be rejected?

Cans should be rejected under all of the listed conditions because each poses a potential risk to food safety and quality. Rust on a can can indicate that the protective coating has been compromised, leading to potential contamination of the food inside. Dented cans may not seal properly, which can allow bacteria to enter, spoil the contents, or lead to a loss of the product's intended flavor and texture.

Additionally, cans without labels cannot provide critical information regarding their contents, expiration dates, and food safety standards. Not knowing what is in a can raises serious concerns about allergens and food safety practices, making it impossible for consumers or food handlers to make informed decisions regarding their use.

Therefore, all of these conditions significantly impact the safety and integrity of the canned goods, justifying the need to reject any cans that exhibit one of these issues.