You can find the answer to this question in Chapter 19 -- the one entitled "Reentry." This chapter describes what happens as the Wakatsuki family is allowed to leave the camp at Manzanar.
Papa buys a car and the family heads back to Los Angeles. As they do that, they start to worry about what kind of a reception they will get from all the white people. They worry that they will be hated. Jeanne imagines that the hate would look like a "dark, amorphous cloud" that would come down on them.
So the best answer of these would be B -- a dark cloud.