A nurse is selecting a family theory to assess a patient's family dynamics. Which family theory best describes a series of tasks for the family throughout its life span?

A) Interactional theory
B) Developmental systems theory
C) Structural-functional theory
D) Duvall's developmental theory

Duvall's developmental theory describes eight developmental tasks of the family throughout its life span. Interactional theory and structural-functional theory are not family theories. Developmental systems theory is an outgrowth of Duvall's theory. The family is described as a small group, a semiclosed system of personalities that interact with the larger cultural system. Changes do not occur in one part of the family without changes in others.