De or het niveauverlaging?

The correct Dutch article is:

de niveauverlaging

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

How to use niveauverlaging

the niveauverlagingde niveauverlaging
this niveauverlagingdeze niveauverlaging
that niveauverlagingdie niveauverlaging
our niveauverlagingonze niveauverlaging
your niveauverlagingjouw niveauverlaging
every niveauverlagingelke niveauverlaging
which niveauverlaging?welke niveauverlaging?
a big niveauverlaging / the big niveauverlagingeen grote niveauverlaging, de grote niveauverlaging