If my memory serves me well, the law which states that a president had to get permission to remove anyone appointed by a past president is <span>The Tenture of Office Act.</span> It was used to impeach Andrew Johnson because he fired a secretary of War Stanton.
The correct answer in this case would be militarism (b). The reason why this is the correct answer because a nation's tendency to expand its armed forces and acquire new and better weapons is also exactly that - militarism.
Other answers here wouldn't be correct because they have different meanings. The only thing that would come close is imperialism which has some similarities but is used in different contexts.
