What was one of the causes of tensions in europe that led to world war i?

assassination of Archduke Franz Ferdinand of Austria-Hungary.

Explanation:

These are the causes of tension in Europe that led to world war one

European Expansionism.

Serbian Nationalism.

The Assassination of Franz Ferdinand.

Conflicts over Alliances.

The Blank Check Assurance: Conspired Plans of Germany and Austria-Hungary.

Germany Millenarianism

These nations were driven by the ideologies of the day: imperialism, which encouraged territorial expansion and empire building; militarism, which promoted a policy of war and the build-up of armies and navies; and nationalism, which focused on unity and loyalty within countries.

The immediate cause of World War I that made the aforementioned items come into play (alliances, imperialism, militarism, nationalism) was the assassination of Archduke Franz Ferdinand of Austria-Hungary. In June 1914, a Serbian-nationalist terrorist group called the Black Hand sent groups to assassinate the Archduke.

the answer to fill in the blank in this question would be the word resource, it is defined as the money, material or people (since human resource is a very valuable good) that a company or a person has at disposition (meaning they can use the resource as they see fit), to be able to complete a task or achieve a goal.  

the answer is a, salt plain