I always prefer 3 piece but ant thing that make you look like professional and confident will work and ask other people that have gone through this process cuz there are special dress for specific impression which you will like to put on management there.
Look professional but practical. You want to send the message that you'll be able to work hard. I'd go with slacks a nice button down or blouse and a blazer or cardigan. Do not wear heels unless they're less than 2 inches.