De or het executieveiling?

The correct Dutch article is:

de executieveiling

Rule Words ending in -ing: almost always de. See the rule

How to use executieveiling

the executieveilingde executieveiling
this executieveilingdeze executieveiling
that executieveilingdie executieveiling
our executieveilingonze executieveiling
your executieveilingjouw executieveiling
every executieveilingelke executieveiling
which executieveiling?welke executieveiling?
a big executieveiling / the big executieveilingeen grote executieveiling, de grote executieveiling