Final answer:
The regulation of an OPO can best be described as ever changing. Laws related to OPOs are subject to regular updates and revisions, which can make the regulatory environment complex and uncertain.
Step-by-step explanation:
The regulation of an OPO (organ procurement organization) can best be described as ever changing. The concept of restrictive practices is continually evolving, as firms seek new ways to earn profits and government regulators define what is permissible. Laws related to OPOs are subject to regular updates and revisions, which can make the regulatory environment complex and uncertain.