De or het zolderopruiming?

The correct Dutch article is:

de zolderopruiming

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

How to use zolderopruiming

the zolderopruimingde zolderopruiming
this zolderopruimingdeze zolderopruiming
that zolderopruimingdie zolderopruiming
our zolderopruimingonze zolderopruiming
your zolderopruimingjouw zolderopruiming
every zolderopruimingelke zolderopruiming
which zolderopruiming?welke zolderopruiming?
a big zolderopruiming / the big zolderopruimingeen grote zolderopruiming, de grote zolderopruiming