You must abide by the rules of the following entities to function legally and ethically, except:

The correct answer is based on the understanding of regulatory and certification bodies that govern professional practices. While the American Board of Certification, state or city government, and the federal government set specific laws, regulations, and certification requirements that professionals must adhere to in order to practice legally and ethically, the Pedorthic Footcare Association primarily serves as a professional organization that provides resources, advocacy, and education rather than enforce legal requirements.

While being a member of the Pedorthic Footcare Association can enhance professional credibility and provide valuable support, it is not mandatory for legal practice in the same way that compliance with government regulations or certification by the American Board of Certification is. Therefore, the Pedorthic Footcare Association's role is supportive rather than regulatory, which clarifies why it is the correct choice in this context.