We are using of law great effect.
A. the arms; in
B. the weapons; of
C. the weapon; with
D. the arm; by
网友回答
A. the arms; in
B. the weapons; of
(答案→)C. the weapon; with
D. the arm; by
解析：考查名词及介词。the weapons of law=法律武器。weapons泛指一切武器，包括具体和抽象的arms一般指武装。with effect 固定搭配，意思是具有成效。故选C。