Which preposition correctly completes this sentence about legal requirements: 'Proof must be made ____ concrete benefits under the regulation'?

A. of

B. for

C. with

D. at

核心考点：固定搭配'make proof of'的介词使用。正确答案A符合'make proof of something'的标准法律英语搭配。B选项暗示目的关系，C选项表示伴随，D选项表位置，均不符合'证据构成要素'的表达需求。易错点：法律文本中特殊介词搭配的记忆。

正确答案：A