What type of verification does the TA provide to confirm eligibility for a SIPRNet token?

The correct answer highlights the process of in-person identification verification as the method used to confirm eligibility for a SIPRNet token by the Trusted Agent (TA). This method is critical because the SIPRNet, or Secret Internet Protocol Router Network, handles classified information, and as such, requires rigorous verification processes to ensure that only authorized individuals receive access.

In-person verification involves the physical presence of the individual seeking access to the SIPRNet. During this process, personal identification documents are typically reviewed, and the identity of the individual is confirmed against stored records. This approach minimizes the risks associated with remote verification methods that could potentially be subject to fraudulent activities.

Furthermore, various types of verification such as online verification or phone call verification might lack the necessary level of security required for access to classified networks. Written confirmation also does not provide the immediacy and certainty that an in-person check can offer. Therefore, in-person identification verification is deemed the most secure and reliable method for confirming eligibility for highly sensitive systems like SIPRNet.