Pls help me with this question. Now, therefore, by virtue of the authority vested in me as President of the United States, and Commander in Chief of the Army and Navy, I hereby authorize and direct the Secretary of War, and the Military Commanders whom he may from time to time designate, whenever he or any designated Commander deems such action necessary or desirable, to prescribe military areas in such places and of such extent as he or the appropriate Military Commander may determine, from which any or all persons may be excluded, and with respect to which, the right of any person to enter, remain in, or leave shall be subject to whatever restrictions the Secretary of War or the appropriate Military Commander may impose in his discretion. The Secretary of War is hereby authorized to provide for residents of any such area who are excluded therefrom, such transportation, food, shelter, and other accommodations as may be necessary, in the judgment of the Secretary of War or the said Military Commander, and until other arrangements are made, to accomplish the purpose of this order.
- President Franklin D Roosevelt, Executive Order 9066, 1942

Which of these would be considered a cause for this policy?
A. most Japanese were not citizens of the United States
B. the Japanese refused to serve in the United States military
C. the Japanese were needed to work at inland defense industries
D. military authorities considered the Japanese a threat to national security