I was brought here under legal guardian ship when i was thirteen years old, I was adopted by a U.S citizen. I became a legal permananet resident when I was 18, now I am trying to apply for my citizenship and I'm not sure which form I should fill out the N-400 or the N-600? I wonder about the form because of the recent application for my U.S. passport was denied, I was trying to apply for the U.S passport under the "parent is a citizen".