De or het productidee?

The correct Dutch article is:

het productidee

This word is not in the word lists we use to double-check answers.

How to use productidee

the productideehet productidee
this productideedit productidee
that productideedat productidee
our productideeons productidee
your productideejouw productidee
every productideeelk productidee
which productidee?welk productidee?
a big productidee / the big productideeeen groot productidee, het grote productidee