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
請問答案應該哪一個? (a.) 或 (b.)??

B字句為非限定

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

我覺得是那個USA把teacher&who隔開，所以不能用限定修飾

我也覺得是(b)是非限定用法，先行詞所指涉的東西已經很清楚了，關代沒有特別幫到甚麼忙。