Final answer:
The Late Adulthood stage is the longest psychosocial development stage, often lasting several decades until the end of life, with changes in social roles, relationships, and cognitive functions.
Step-by-step explanation:
The psychosocial development stage of maturity that lasts the longest is c) Late Adulthood stage:
Adulthood is a significant portion of an individual's lifespan, potentially extending up to 80 years or more. It begins around 20 years old and encompasses three main stages: early adulthood, middle adulthood, and late adulthood. Among these, late adulthood spans the longest period, often covering several decades until the end of life.
While physical growth tends to decelerate after early adulthood, significant changes in psychosocial and cognitive domains continue throughout late adulthood. Social roles, relationships, and cognitive functions continue to evolve as new challenges and opportunities arise. Aging individuals often face retirement and adjust to the physical changes that come with aging, while also possibly enjoying the rewards of a lifetime of experiences and relationships.