To obtain information about a vehicle crossing the Mexican border, which transaction should be submitted with a state POE code of NA?

The correct choice is the first option, which pertains to submitting a transaction to obtain information regarding a vehicle crossing the Mexican border with a state Port of Entry (POE) code of NA. When using the RQ transaction, it specifically requests information tied to a vehicle, such as its registration or any related records. This is crucial for evaluating the vehicle's status and history for border security and law enforcement purposes.

Understanding the context of the other options helps clarify the choice. The ES transaction is primarily used for requests related to event-specific inquiries, while CT transactions focus on criminal history checks or records. The MV transaction is centered around motor vehicle records but might not directly cater to the specific context of border crossing information. Therefore, the use of RQ stands out as the most appropriate action in this scenario for acquiring relevant vehicle information when crossing the border.