She is the only one of the students _______ able to answer t

She is the only one of the students _______ able to answer this questionA.who isB.who areC.that isD.that are

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A解析本题修饰一个表示人的代词one，是一个定语从句，修饰人关系词用who，who在从句中作主语，先行词为单数，故who后的be动词用is，故本题选A。