De or het slotdiscussie?

The correct Dutch article is:

de slotdiscussie

Rule Words ending in -tie and -sie: almost always de. See the rule

How to use slotdiscussie

the slotdiscussiede slotdiscussie
this slotdiscussiedeze slotdiscussie
that slotdiscussiedie slotdiscussie
our slotdiscussieonze slotdiscussie
your slotdiscussiejouw slotdiscussie
every slotdiscussieelke slotdiscussie
which slotdiscussie?welke slotdiscussie?
a big slotdiscussie / the big slotdiscussieeen grote slotdiscussie, de grote slotdiscussie