De or het blokmarkering?

The correct Dutch article is:

de blokmarkering

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

How to use blokmarkering

the blokmarkeringde blokmarkering
this blokmarkeringdeze blokmarkering
that blokmarkeringdie blokmarkering
our blokmarkeringonze blokmarkering
your blokmarkeringjouw blokmarkering
every blokmarkeringelke blokmarkering
which blokmarkering?welke blokmarkering?
a big blokmarkering / the big blokmarkeringeen grote blokmarkering, de grote blokmarkering