Question: NAME_1 uses a “sliding scale” that is based on a client’s current income to set his fees for therapy. NAME_2’s practice is:
A: ethically acceptable since it serves the best interests of his clients.
B: explicitly recommended in the ethical guidelines.
C: ethically unacceptable since it treats clients inequitably.
D: explicitly prohibited in the ethical guidelines.
Please eliminate two incorrect options first, then think it step by step and choose the most proper one option.