The answer is gender identity; gender expression
This option suggests that children develop their gender expression and that gender roles may vary based on context. However, gender expression is typically how individuals present their gender to the world, which can indeed vary based on context, but it is not the primary concept that stabilizes over time as children develop.
This option correctly identifies that as children develop mentally and gain more experiences, they begin to develop their gender identity, which tends to stabilize over time. Gender expression, on the other hand, can vary based on context, as it involves the external presentation of one's gender, which can change depending on social settings, cultural norms, and personal preferences.
Sexual orientation refers to the pattern of emotional, romantic, or sexual attraction to others, which is not the primary focus of the question regarding stabilization over time. Gender socialization is the process by which individuals learn the gender norms of their culture, but it is not something that stabilizes in the same way as gender identity.
This option suggests that gender socialization stabilizes over time, which is not accurate. Gender socialization is an ongoing process. Sexual orientation is not typically something that varies based on context in the same way that gender expression does.