Either Carol or Grace ______ to the concert,  but one of them ha

Either Carol or Grace ______ to the concert,  but one of them has to stay home.
A、is coming
B、are coming
C、will coming
D、have come
【正确答案】：A
【题目解析】：以or, either....or, neither...nor等连接的名词（代词）做主语时，谓语动词的单复数应根据就近一致的原则。