Clothes Choice Help?!?!?1?!? please!?

Im going on a trip with my class to Washington D.C. and we are going to Arrlington Cemetary and it has a specific dress code for it and it says for my trip rules: no jeans (or jean shorts) no named sweatshirts, and no casual tees. so i mean it has to be nice clothing but i have no idea what to wear and still look good.