The only options to run are the 100m and 400m.
That's it.
Why is this such a big event? It's silly. I get that these qualify nations for entering 4x100 and 4x400 later but if it's going to be an event of "relays" why not include other distances as well? Even as novelty events. 4x800, DMR, SMR, etc etc.
Otherwise, we should just call it what it is: "Qualifying Rounds for World Championships Relays"