Did I acquire derivative citizenship? What type of visa is considered "admission to the U.S. for lawful permanent residence"?

Hello, I think I meet the requirements for the application for a certificate of citizenship through my father, since he was naturalized before I turned 18 and before 2001. In form n-600, one of the requirements which I'm not sure I meet is whether I was brought to the U.S. "for lawful permanent residence." Is there a separate visa that indicates that? My mother recalls us being brought to the U.S. through a visitor's visa, but cannot remember the exact date or details. I became a permanent resident by April of 2001... if that helps. Thank you!