Final answer:
The stage of adulthood where a person takes on new roles and activities is called middle adulthood, spanning from mid-30s to mid-60s.
Step-by-step explanation:
Taking into consideration the stages of adulthood where an individual accepts new roles and activities in life, the stage you are referring to is middle adulthood or middle age. Middle adulthood usually begins in the mid-30s and continues until the mid-60s. It's a period characterized by achieving career goals, raising a family, and experiencing physical signs of aging such as wrinkles and gray hair. Health risks also increase during middle adulthood, with conditions like heart disease, cancer, and diabetes becoming more common.