Many Southerners felt betrayed by President Zachary Taylor because he was a Southerner who favored California's admission as a free state
D: Congress could go around state government and act directly to individual citizens
Chinese immigrants were cast as outcasts in Californian society, because of cultural differences - customs, clothing, beliefs, food, language etc -. The response to those differences caused Chinese immigrants to form their own community called Chinatowns.
Nativists thought Chinatowns were dangerous but necessary to help Chinese immigrants to assimilate, they also thought Chinatown was useful because it was used to separate immigrants from other residents.