Answer :

WW1 started as a conflict between Austria and Serbia and then Serbia was supported by Russia. Because of the triple alliance and the triple entente, other countries who had agreements with Russia and Austria entered the conflict, thus engaging all of the major European power and starting a World War

Answer

increasing tensions between European Countries

Explanation

The Tripple Alliance  was formed by Germany,Austria-Hungary and Italy.They promised to each other that they will give each other military support in case of war. They came to an agreement to this by signing an agreement document .The Alliance agreement stated it was 'essentially defensive and conservative' with the aim of stopping anyone who 'might threaten' the three nations. The proximate cause of the outbreak of combat was the Austrian Declaration of War on Serbia. Italy did not join the war because Austria and Germany had attacked but the Triple Entente was the second treaty in the cascade to WWI. The tipple Entente was an alliance of Britain, France and Russia.They formed this alliance for the purposes of counterbalancing the threat by the Tripple alliance of  Germany, Austria, and Italy. The contribution of the world war by these alliances was that if a member from one alliance declared war on a member from the other alliance, the conflict would quickly arise.