Captain's log, Stardate 3842.3. We have departed Vulcan for the neutral planetoid code-named Babel. Since it is in our sector, the Enterprise has been assigned to transport  ambassadors of Federation planets to this vitally important council.
was chosen because Babel was in "its" sector. No other ambassador transports were mentioned.
However, the prominent ambassadors (Vulcan, Andor, Tellar) were on board, but we never learned the whereabouts of the ambassador of Earth.