Mrs. Norpa was new to our school.
Mrs. Norpa was this little English teacher from USA ____ always wore a
black leather skirt, even though she was fifty years old.
(a) who (b),who (c) which (d) ,which
请问答案应该哪一个? (a.) 或 (b.)??

B字句为非限定

"Practical English Usage" by Michael Swan, 3e130 cleft sentences (1): ....-> 1 ...

我觉得是那个USA把teacher&who隔开，所以不能用限定修饰

我也觉得是(b)是非限定用法，先行词所指涉的东西已经很清楚了，关代没有特别帮到什么忙。