De or het letteromzetting?

The correct Dutch article is:

de letteromzetting

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

How to use letteromzetting

the letteromzettingde letteromzetting
this letteromzettingdeze letteromzetting
that letteromzettingdie letteromzetting
our letteromzettingonze letteromzetting
your letteromzettingjouw letteromzetting
every letteromzettingelke letteromzetting
which letteromzetting?welke letteromzetting?
a big letteromzetting / the big letteromzettingeen grote letteromzetting, de grote letteromzetting