大全-3-5，如何排除选项A和B？

大全-3-5.   A weapons-smuggling incident recently took place in country Y. We all know that Y is a closed society. So Y’s government must have known about the weapons.

Which of the following is an assumption that would make the conclusion above logically correct?

(A) If a government knows about a particular weapons-smuggling incident, it must have intended to use the weapons for its own purposes.

(B) If a government claims that it knew nothing about a particular weapons-smuggling incident, it must have known everything about it.

(C) If a government does not permit weapons to enter a country, it is a closed society.

(D) If a country is a closed society, its government has a large contingent of armed guards patrolling its borders.（E）

(E) If a country is a closed society, its government has knowledge about everything that occurs in the country.

A是由结论推出的一个必要条件，为什么不可以作为结论的一个assumption呢？B如何取非排除呢？

如果把A改成：If a government knows about a particular weapons-smuggling incident,it must have knowledge about everything that occurs in the country.对不对呢？