Trumpet Voluntary

Ok, so we hear it at many weddings, so it should be simple when requested to find the music, play the music and move on right? Well my cousin asked me to play it for her wedding and since I can't get in touch with the organist, I started looking online. I've found it in at least 5 different keys and at least 3 different arrangements. So which do I pick? Do I gamble the the organist will have it in a certain key? The last time I played it, the bride gave me music and the organist showed up and said he knew it in a different key. Thank God for the transposition wheel on the organ.

This should be simple!!! One key, one mel'dy, one tune of all, we are one trumpet when we play.... (pardon the bad and I mean BAD rip off of One Bread, One Body).