The least justification for considering engineering or geoscience professionals as "professional" comes from their ability to be self-employed and work directly with clients. While this is a feature of professional work, it does not inherently require or ensure adherence to a high standard of ethical or professional conduct, nor does it necessitate specialized knowledge or responsibility to the public. In contrast, statements B, C, and D directly relate to the core definitions of professionalism, including responsibility to the public, specialized knowledge, and regulation by professional standards, which are key elements that define a profession in a traditional sense​​.