De or het projectondersteuning?

The correct Dutch article is:

de projectondersteuning

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

How to use projectondersteuning

the projectondersteuningde projectondersteuning
this projectondersteuningdeze projectondersteuning
that projectondersteuningdie projectondersteuning
our projectondersteuningonze projectondersteuning
your projectondersteuningjouw projectondersteuning
every projectondersteuningelke projectondersteuning
which projectondersteuning?welke projectondersteuning?
a big projectondersteuning / the big projectondersteuningeen grote projectondersteuning, de grote projectondersteuning