It may rain hard this weekend,---the football match will hav

B
which这个关系代词指物时,除了在定语从句里作主语和宾语外,也可以作定语修饰名词,相当于this或that,in which case在这里可以相当于in that case,但是逗号是不能分隔两个独立的句子的,只能是一句主句,一句从句,所以只能选择B,实际上这里的in which case相当于and in that case的意思.又如：
A lot of people want to learn the Spanish language,which language is very difficult to learn.
希望我能帮助你解疑释惑.