De or het kuilharing?

The correct Dutch article is:

de kuilharing

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

How to use kuilharing

the kuilharingde kuilharing
this kuilharingdeze kuilharing
that kuilharingdie kuilharing
our kuilharingonze kuilharing
your kuilharingjouw kuilharing
every kuilharingelke kuilharing
which kuilharing?welke kuilharing?
a big kuilharing / the big kuilharingeen grote kuilharing, de grote kuilharing