英语定语从句OnAprilfools'Day,manypeopleplaytricksontheonetheyarefamiliarwith
OnAprilfools'Day,manypeopleplaytricksontheonetheyarefamiliarwith.
OnAprilfools'Day,manypeopleplaytricksontheone【that】theyarefamiliarwith.
OnAprilfools'Day,manypeopleplaytricksontheone【who】theyarefamiliarwith.
OnAprilfools'Day,manypeopleplaytricksontheone【whom】theyarefamiliarwith
这四句话,哪一个对?为什么?