De or het letterenstudie?

The correct Dutch article is:

de letterenstudie

How to use letterenstudie

the letterenstudiede letterenstudie
this letterenstudiedeze letterenstudie
that letterenstudiedie letterenstudie
our letterenstudieonze letterenstudie
your letterenstudiejouw letterenstudie
every letterenstudieelke letterenstudie
which letterenstudie?welke letterenstudie?
a big letterenstudie / the big letterenstudieeen grote letterenstudie, de grote letterenstudie