De or het trapondersteuning?

The correct Dutch article is:

de trapondersteuning

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

How to use trapondersteuning

the trapondersteuningde trapondersteuning
this trapondersteuningdeze trapondersteuning
that trapondersteuningdie trapondersteuning
our trapondersteuningonze trapondersteuning
your trapondersteuningjouw trapondersteuning
every trapondersteuningelke trapondersteuning
which trapondersteuning?welke trapondersteuning?
a big trapondersteuning / the big trapondersteuningeen grote trapondersteuning, de grote trapondersteuning