The Fact That President Roosevelt Ordered the Placement of Japanese

The fact that President Roosevelt ordered the placement of Japanese Americans in relocation camps (and the order was upheld in  Korematsu v. United States) , yet German Americans were not rounded up (despite pro-Nazi groups) , suggests that

A) Japanese Americans were more numerous than German Americans.
B) German Americans were more numerous than Japanese Americans.
C) racial animosity was more important than security concerns.
D) geographic distribution of these groups made it easier to locate Japanese Americans.
E) Japanese Americans were a greater security threat, while German Americans were only an economic threat.