Final answer:
Jonas goes through a major psychosocial change, gaining a new understanding of his community and developing his own moral and ethical values, paralleling the adolescent journey towards identity formation and self-discovery.
Step-by-step explanation:
The major change that Jonas goes through in chapters 12-20 of The Giver is A. He gains a new understanding of his community. During these chapters, Jonas begins to receive memories from the Giver, which expands his understanding of feelings, color, and the depth of human experience—all aspects absent from his previously monochromatic and emotionless community. The transformative process of receiving memories significantly shifts Jonas's perspective, instilling in him a profound sense of empathy, the awakening of emotional depth, and the realization of the sacrifices made for societal conformity and stability.
As illustrated through various pieces of literature and psychological research, this sort of psychosocial change is typical during significant phases of human development, such as adolescence, wherein individuals begin to develop their own system of moral and ethical values. Jonas's transition mirrors the typical adolescent journey of self-discovery and the struggle with the concept of identity versus role confusion, as described by Erikson's stages of psychosocial development.