Which factor was an important contribution to the start of the world war 1

The assassination of Archduke Franz Ferdinand of Austria-Hungary.

Explanation:

The start of of the first world war was the assassination of Austrian archduke, Franz Ferdinand and his wife, on 28th June 1914 by Bosnian revolutionary, Gavrilo Princip. Princip was part of an assassin group with 5 other people led by Danilo Ilića, Bosnian Serb and a member of the Black Hand secret society. The political objective of the assassination was to break off Austria-Hungary's South Slav provinces so they could be combined into a Yugoslavia.

the navigation act prevented the colonies from exporting to countries other than britain and it prevented the importation of goods by other countries as well. so i believe the correct answer is d. other nations could not deliver goods to the colonies.

hope this .