De or het portretstudie?

The correct Dutch article is:

de portretstudie

How to use portretstudie

the portretstudiede portretstudie
this portretstudiedeze portretstudie
that portretstudiedie portretstudie
our portretstudieonze portretstudie
your portretstudiejouw portretstudie
every portretstudieelke portretstudie
which portretstudie?welke portretstudie?
a big portretstudie / the big portretstudieeen grote portretstudie, de grote portretstudie