Which of the following prepositional phrases is an adverbial of concession?
【正确答案】 C
【答案解析】选项A中介词短语作目的状语;选项B中介词短语也作目的状语;选项C中介词短语作让步状语,for all意为“尽管”,为正确答案。选项D中介词for引导间接宾语their son。