Which relative pronoun is correct?

the speaker kicked off the conference turned out to be quite dull.

who
whom
which
that

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."

third person

explanation:

note the usage of names and pronouns, "james" & "the old man". this alone can confirm it as third person, as first person uses "i" and the like, while second person uses "you" and the like.

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