Final answer:
In Erikson's stages of psychosocial development, when a person is in their 30s, the related challenge is Intimacy vs. isolation.
Step-by-step explanation:
According to Erik Erikson, when a person is in his or her 30s, intimacy is related to Intimacy vs. isolation. This stage occurs during early adulthood, coinciding with the 20s through early 40s, where the focus is on forming intimate relationships, both in friendship and love. Erikson believed that developing a sense of self in adolescence is a prerequisite for forming these intimate relationships. Those who do not develop a strong sense of self may experience feelings of loneliness and emotional isolation.