De or het optiespecialist?

The correct Dutch article is:

de optiespecialist

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

How to use optiespecialist

the optiespecialistde optiespecialist
this optiespecialistdeze optiespecialist
that optiespecialistdie optiespecialist
our optiespecialistonze optiespecialist
your optiespecialistjouw optiespecialist
every optiespecialistelke optiespecialist
which optiespecialist?welke optiespecialist?
a big optiespecialist / the big optiespecialisteen grote optiespecialist, de grote optiespecialist