Final answer:
Clotilde did not fact-check her aunt's statement about meat consumption and cancer, thereby violating the ethical speaking guideline of honesty.
Step-by-step explanation:
Clotilde violated the guideline for ethical speaking which states that a speaker should be honest in their presentation. By not verifying the claim about meat consumption being the number one cause of cancer in the United States, she failed to ensure the accuracy of the information she presented to her audience. An ethical speaker has the responsibility to confirm the validity of their content before sharing it, making sure that the facts and statements in their speech are correct and supported by data or credible sources. In this case, Clotilde should have researched the link between meat consumption and cancer before including it in her speech.