Final answer:
At the end of the preschool years, children have developed a gender identity and an understanding of gender roles.
Step-by-step explanation:
At the end of the preschool years, when children understand that their sex is a permanent characteristic of the self, they have developed a gender identity. This means that they have a strong sense of whether they are a boy or a girl and identify themselves accordingly. They have also developed an understanding of the culturally appropriate gender roles associated with their gender. Gender identity and gender roles are important aspects of a person's social and psychological development.