As the name suggests, conflict theory describes the perspective that holds that all of society is a constant struggle for social dominance between competing groups. The gender stratification that comes about from competition between men and women is but one example of this phenomenon.
While there is some disagreement on the specifics, for the most part, feminist theory holds that gender stratification comes about as a result of systemic discrimination against women on an individual level, which manifests in gender inequality in society as a whole.
Symbolic interactionism seeks to understand society through an examination of the role of symbols in social interaction. According to this approach, gender stratification comes about due to the different manners of symbolic interaction related to conceptions of gender that are conditioned into people as a result of socialization.
In functionalist theory, society is viewed as a complex system that seeks to maximize the efficiency of its parts. According to this theory, gender stratification comes about because it is the most effective and efficient manner of dividing labor.