What unethical practice has John engaged in by spreading false claims about his competition?

The situation described involves John spreading false claims about his competition, which directly aligns with the concept of defamation. Defamation refers to the act of making untrue statements about an individual or business that can harm their reputation. In this case, John's actions of spreading false claims can damage his competition's public standing and consumer trust, fitting the legal and ethical breach defined by defamation.

This practice is taken seriously in both legal and ethical standards, as it undermines fair competition and can lead to significant consequences for the party defamed. By making these untrue statements, John is acting unethically within the realm of business practices, as he is not only misleading consumers but also attempting to gain an unfair advantage over his competitors.

Other options, while potentially serious in different contexts, do not accurately describe the behavior in question. Fraud involves deceptive practices designed to secure unfair or unlawful gain, conspiracy refers to an agreement between two or more parties to commit an unlawful act, and malpractice typically pertains to professional misconduct or negligence, which doesn't apply in this instance. Thus, defamation is the most fitting description of John's unethical conduct.