Answer: ethos, an appeal based on the speaker’s credibility
Step-by-step explanation:
Ethos is a persuasion technique that aims to convince the listeners of the claims made by the speaker by basing it on the speaker's credibility to be able to say such things. For instance, a doctor giving medical advice and saying it is based on their years of experience in medicine.
In this scenario, President Roosevelt is using ethos to convince Americans that he is leaving the internment of Japanese-Americans at the discretion of the Secretary of War and any appropriate Military Commander and that they are credible enough to carry out such a task because he has authorized it as the President.