A client who had successfully mastered Erikson's psychosocial stage of generativity versus stagnation would be...

Erikson's stage of generativity vs. stagnation, which typically occurs in middle adulthood, is characterized by a desire to contribute to the next generation through activities such as mentoring, parenting, or productive work. Successful mastery results in behaviors like mentoring youth and making contributions that benefit others, reflecting a sense of generativity.