A. Not the best answer. Baltes explains human development as occurring across the lifespan and as being affected by four mutually influential principles.
B. Not the best answer. Circumstances and primary interests of individuals in each category characterize periods of adult development.
C. The best answer. The meanings of age as described by Papalia et al. are influenced more by the way one behaves, functions, or thinks than by chronological age.
D. Not the best answer. Normative influences are similar across individuals; nonnormative influences are atypical events experienced individually.
E. Not the best answer. Bronfenbrenner explains that understanding the individual depends on understanding multiple levels of environmental influence.