De or het projectidee?

The correct Dutch article is:

het projectidee

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

How to use projectidee

the projectideehet projectidee
this projectideedit projectidee
that projectideedat projectidee
our projectideeons projectidee
your projectideejouw projectidee
every projectideeelk projectidee
which projectidee?welk projectidee?
a big projectidee / the big projectideeeen groot projectidee, het grote projectidee