To "get" an allusion, what do readers need to know? basic information about a historical topic
how to perform complex math equations
all of the most important current news stories
the jargon used to discuss scientific topics

because of all the immigration, america became one big melting pot. the diversity of cultures from all over the world made america somewhat divided as well. people that immigrated stayed with their kind, and their traditions, while native born americans stayed with their kind and their traditions. normally, people born in american scorned the immigrants as well. the new religions also divided america. in summary, it took away from the american culture and identified america as the "melting pot."

the correct answer is (a) . answer should be simple, clear and brief.