Final answer:
a. Obtaining a prescription for reading glasses. The developmental task of middle adulthood exemplified by serving as a surrogate for childbirth is rooted in the concept of generativity, one of the crucial aspects defined by Erik Erikson for this stage of life.
Step-by-step explanation:
The action that demonstrates a primary developmental task of middle adulthood is b. Agreeing to serve as a surrogate for childbirth. This task is associated with the concept of generativity, which is the process of making a significant contribution to future generations, a core task Erik Erikson identifies for this life stage. Serving as a surrogate is an example of contributing to the development of others, displaying a sense of community and generativity.
**a. Obtaining a prescription for reading glasses** demonstrates a primary developmental task of middle adulthood. This stage, typically occurring between the ages of 40 and 65, is characterized by addressing aging-related changes. The need for reading glasses reflects adjustments to changing vision, a common occurrence in middle adulthood.
This task signifies acknowledging and adapting to age-related physiological changes. In contrast, options b, c, and d involve various aspects of health and reproduction but may not directly represent the primary developmental task related to aging and adapting to physical changes that is characteristic of middle adulthood.