what question correct or incorrect

什麼類型的孩子是在這學院上學的?
The following question, which one is correct?

What kind of kids go to this college? (correct or incorrect) 這問句是不是不完整, 應該是 What kind of kids going to this college are they? (correct ?)

What kind of kids that go to this college? (incorrect ?)
What kind of kids that go to this college are they? (correct ?)
What kind of kids who go to this college? ( incorrect ?)
What kind of kids who go to this college are they? (correct ?)