Final answer:
The least likely reason Selma is feeling much better is the therapist maintaining a professional distance, as empathy, new perspectives, and hope are direct contributors to better emotional well-being.
Step-by-step explanation:
Among the listed reasons why Selma has been feeling much better after three months of therapy, the option that is most likely NOT a reason is that 'Her therapist maintains a professional distance.' Effective therapy often involves both professional boundaries and a sense of care and empathy from the therapist. While a professional distance is important for maintaining objectivity, it is typically the therapist's empathic approach, provision of new perspectives, and instillation of hope in the client that directly contribute to improvements in emotional well-being.