De or het samenbundeling?

The correct Dutch article is:

de samenbundeling

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

How to use samenbundeling

the samenbundelingde samenbundeling
this samenbundelingdeze samenbundeling
that samenbundelingdie samenbundeling
our samenbundelingonze samenbundeling
your samenbundelingjouw samenbundeling
every samenbundelingelke samenbundeling
which samenbundeling?welke samenbundeling?
a big samenbundeling / the big samenbundelingeen grote samenbundeling, de grote samenbundeling