The business document would be most appropriate in this scenario is an email.
* Email stands for electronic mail and is used for conveying a message instantly within seconds.
* In this scenario, Josh wants to convey his good wishes on the same day of the meeting so email would be the best option considering the time period.
* Emails are quick, easy and convenient and can also be used for business purposes.
* The other modes will be quite consuming and hence not preferred in this case.