How Has the Study of Adult Development Changed Over Time

How has the study of adult development changed over time?

A) After the population shift of the 1990s, developmental theorists focused their studies more on adult development, leading to a diminished interest in child and adolescent development.
B) It was extensively studied during the social justice conscience efforts of the 1960s, but interest faded out by the 1980s.
C) Today, researchers have expanded their work and are beginning to study emerging adulthood more.
D) Developmental theorists overlooked this field of study because adulthood developmental changes are primary physical, and not social and cognitive.