De or het clustervorming?

The correct Dutch article is:

de clustervorming

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

How to use clustervorming

the clustervormingde clustervorming
this clustervormingdeze clustervorming
that clustervormingdie clustervorming
our clustervormingonze clustervorming
your clustervormingjouw clustervorming
every clustervormingelke clustervorming
which clustervorming?welke clustervorming?
a big clustervorming / the big clustervormingeen grote clustervorming, de grote clustervorming