Which of the following is a notary's primary responsibility?

A notary's primary responsibility is centered on authenticating signatures and documents. This duty is fundamental to the notary's role in preventing fraud and ensuring that documents are executed correctly. By verifying the identity of the signers and witnessing their signatures, the notary helps to confirm that the individuals are who they claim to be and that they are signing the documents willingly and without coercion. This process establishes trust in the transaction and provides a level of assurance that the documents have not been altered after signing.

Other responsibilities of a notary, like ensuring the signer understands the document, collecting fees, and providing legal advice, do not constitute the main duty of the notary. While a notary might encourage signers to understand what they are signing and may charge for their services, providing legal advice is explicitly outside the scope of a notary's role, as they must remain neutral and not engage in the practice of law. Thus, the primary focus on authenticating signatures and documents reinforces the integrity of the notarization process.