What must be true about the signer's signature on a notarized document?

The correct choice emphasizes that the signer's signature on a notarized document should be similar to the signature on their identification card. This similarity is important because it helps the notary public to identify and verify the signer's identity, ensuring that the person signing the document is indeed the same person who is identified in the documentation provided.

In the process of notarization, the notary checks the identification to confirm that the signatures align closely enough to reasonably assert that the signer is authenticating the document. While it is not necessary for the signatures to be identical, noticeable differences may raise concerns about the legitimacy of the signature, increasing the risk of fraud. Therefore, a signature that bears similarities—enough for the notary to make a confident verification—provides a level of assurance that is essential to the notarization process.

Other potential answers, such as suggesting the signature should be identical or allowing for great differences, do not align with the purpose of ensuring accurate identification during the notarization process.