What Does It Mean to Be 'Cisgender

What does it mean to be 'cisgender'?

A) you perform your gender in a culturally normative way and one that matches your apparent sex
B) you perform your gender in a culturally normative way
C) it's the same as 'transgender'
D) you perform your gender in a way that matches gender expectations for the opposite sex
E) you are in a culturally constructed 'gender crossover' role and everyone, strangers included, know that you are in this role