Final answer:
Carl Rogers' client-centered therapy requires the therapist to provide unconditional positive regard, which is the necessary element for an effective therapeutic relationship.
Step-by-step explanation:
According to Carl Rogers, a proper therapeutic relationship between therapist and client is essential for success in therapy. Rogers' approach, known as client-centered therapy, emphasizes that the therapist must provide unconditional positive regard, genuineness, and empathy for effective therapeutic outcomes. Of the options provided, unconditional positive regard is the element that Rogers believed was necessary in a therapeutic relationship. It means that the therapist accepts and supports the client regardless of what the client says or does, creating a safe and supportive environment for personal growth and self-exploration.