?why not
: the whole form of the sentence is this
I think that none of them are correct
This is a noun clause and the word that is a noun clause marker
in noun clauses you can simply omit that
( here that is omitted to make the sentence shorter ( along with keeping its original meaning
I think none of them are correct
: Navigate to section Din link below
http://faculty.deanza.edu/flemingjohn/stories/storyReader$23