What is correct about digital signatures?

A digital signature is produced by hashing the document's content and encrypting that hash with the signer's private key. Because the hash is derived from the exact bytes of that specific document, any different document will produce a different hash, rendering a transplanted signature cryptographically invalid. This binding ensures integrity and non-repudiation for that document only.

Digital signatures cannot be reused across documents of the same type because each document produces a unique hash value regardless of document category.

The reason a digital signature is non-transferable is that it is an encrypted hash of the document content, not because it is plain text.

Digital signatures are not universally reusable tokens - each signing operation produces a unique output tied to the specific document being signed, not a credential valid for any document.