Final answer:
The best example of ethos is when most federal judges agree that a plan is unconstitutional.
Step-by-step explanation:
The best example of ethos among the given options is A. Most federal judges agree that the plan is unconstitutional. Ethos is an appeal to ethics or credibility, and it is based on the speaker's reputation, authority, or expertise on the subject. In this example, the statement that most federal judges agree about the plan being unconstitutional appeals to their expertise and credibility, making it an appeal to ethos.
Learn more about ethos in persuasion