Final answer:
The correct response is to provide understanding and support to the client by acknowledging their feelings of depression and offering companionship in a difficult time. It's crucial to validate the client's feelings and create a supportive therapeutic environment.
Step-by-step explanation:
An appropriate therapeutic response when a client expresses feelings of depression is to show empathy and understanding. A compassionate response like C. 'I can understand that you are feeling depressed right now. It was a very difficult decision to make. I'll sit with you for a while.' provides a supportive environment and validates the client's feelings, which is crucial in the therapeutic process. This approach aligns with treating depression symptoms which include sadness, loss of interest, feelings of worthlessness, and hopelessness, among others. Meanwhile, treatments for depression involve psychotherapy, medication, and lifestyle changes, all requiring professional guidance and a sympathetic approach to initiate and maintain an effective treatment plan.