question: Q:You regularly waive the co-payment for your low-income clients who are covered by insurance and believe this is acceptable since you normally bill your clients on a sliding fee scale. This is:? 
  A:a common and ethical practice.;B:ethical as long as you don't bill the insurance company for an increased hourly fee in order to collect your full fee.;C:ethical as long as the insurance company does not explicitly prohibit such arrangements.;D:ethical only if the insurance company is aware of the arrangement.