Final answer:
Erikson's sixth stage, which focuses on the challenge of forming intimate relationships versus facing social isolation, is called 'Intimacy vs. isolation.' The correct option is D.
Step-by-step explanation:
Erikson's sixth stage focuses on establishing intimate relationships or risking social isolation and is known as Intimacy vs. isolation. During this stage, individuals in early adulthood (i.e., 20s through early 40s) are primarily concerned with forming intimate, loving relationships with other people.
Success in this stage will lead to strong relationships, while failure results in loneliness and emotional isolation. Answering the question, the correct option is D. Intimacy vs. isolation.