Final answer:
According to Erik Erikson's theory, middle childhood is the stage of industry versus inferiority, where children develop a sense of pride and accomplishment or feel inferior and inadequate(option d).
Step-by-step explanation:
In Erik Erikson's theory of psychosocial development, middle childhood is associated with the stage of d) industry versus inferiority.
This stage occurs between the ages of six and ten, during which children compare themselves to their peers and develop a sense of pride and accomplishment in their schoolwork, sports, social activities, and family life, or they may feel inferior and inadequate if they don't measure up.