What is the No.1 rule a lady must keep in mind when dressing for an office party?

A、Even if the party is casual, do not wear attire that is too casual.;
B、When you're choosing your outfit for an office party, you wear something that is flattering for your body shape. ;
C、Never wear something too revealing.;
D、Don't wear sneakers, animal prints and even if you wear jeans wear dark jeans in a classy model.