Which of the following is part of the credentials verification process?

Review of public and proprietary data sources is a crucial part of the credentials verification process because it involves checking the authenticity of the signer's identity and credentials against established records. This approach ensures that the notary is verifying the individual's identity through reliable and official means, reducing the risk of fraud. By accessing various data sources, a notary can confirm important details, such as names, addresses, and other identifying information to ensure they match with the information provided by the signer.

The other options, while they may involve interactions or documentation, do not specifically pertain to the fundamental process of verifying credentials based on established data. Conducting an interview, for example, might provide additional context about the signer but is not a formal method of credential verification itself. Preparing an official report pertains more to the documentation process rather than verification, and notarizing a witness statement involves a different function altogether, focusing on the witnessing of signatures rather than the verification of the signer's credentials.